### Working with Percent: Tax, Tip, and Discount

```Please get ready to learn.
1. Copy Agenda for the week.
2. Glue your quiz into your
Journal. You need scissors.
3. Write title and date in Math
Journal.
4. Have sharpened pencil and
allow you to use it! 
WARM-UP…SHOW ALL WORK IN JOURNAL
Use a percent bar model to find 6% of 1.
0
X
X = 0.06
0%
6%
0
X
0%
6%
100%
2
100%
What would be 6% of 2?
X = 0.12
1
WHEN DO WE USE PERCENT IN REAL LIFE?
Brainstorm….
Within your group, discuss when we use percent in our lives.
•
To tell which juice has the most concentrate
•
•
To find sales tax
•
To find tip
•
To find a sale price
Today’s lesson is all about making connections. Connecting the models to
number sentences. Connecting how to use percent in real-world situations.
It’s like coming to the climax of a great story and you will finally get to see
how it plays out!!!
SALES TAX
In Idaho, the sales tax is 6%. Discuss in your groups what this means.
Sales tax is an amount that is added to the price of a purchase.
For every one dollar there is \$0.06 tax.
How much tax for two dollars? Three dollars?
sentence could you write to calculate the tax
for any dollar amount?
0.06 x Dollars= tax
Compare this multiplication sentence to your
bar models.
MAKING CONNECTIONS
6% of 1 is 0.06.
0.06 x Dollars = tax
So,
0
X
0%
6%
0
X
0%
6%
1
100%
2
100%
0.06 x 1 = 0.06
And,
6% of 2 is 0.12
0.06 x 2 = 0.12
Can you see that the word “of”
means to multiply?
MAKING CONNECTIONS
In your groups, discuss how would you write these as a multiplication
sentences? Then solve.
What is 4% of 20?
0.04 x 20 = 0.8
What is 5% of 25?
0.05 x 25 = 1.25
What is 6% of 36?
0.06 x 36 = 2.16
APPLY WHAT YOU JUST LEARNED…
1. If you made a \$50 purchase, what is the tax (in Idaho) on your
purchase?
What would be the total cost of your purchase?
2. You just bought a pizza for \$15.98 plus tax. What is the total cost of
your pizza? (Round the tax to the nearest cent.)
3. You and your friends stopped at the Maverick while walking home from
school. You bought a small drink for \$1.29 and a bag of sunflower
seeds for \$3.49. How much did you spend total including tax? (Always
round tax to the nearest cent.)
TIP
It is social etiquette to tip a server (someone who waits on you), as in a
restaurant. Ten percent would be on the low end, 15% is middle ground,
and 20% would be appropriate for excellent service. This percentage is
At a restaurant while on vacation, you order a meal that costs \$12. You
leave a 20% tip. The sales tax in that state is 5%. What is the total cost
of the meal?
1. Find the tip.
20% of \$12 = 0.20 x 12 = 2.40
2. Find the sales tax.
3. Add the food bill, tip, and sales tax.
5% of \$12 = 0.05 x 12 = 0.60
12 + 2.40 + 0.60 = \$15.00
APPLY WHAT YOU JUST LEARNED…
Your Mom took you out to lunch at your favorite Chinese restaurant. You
ordered the Mandarin Chicken for \$8.95, and your Mom ordered the
General Tao Chicken for \$9.25. She left a 15% tip. If tax was 6%, how
much did your Mom spend on lunch?
\$8.95 + \$9.25 = \$18.20
18.20 x 0.15 =
2.73
18.20 x 0.06 =
1.092 (round to nearest cent)
Total =
\$22.02
Discuss in your group WHY you calculate the tax
and tip separately and then add them all together.
DISCOUNT
To find a discount or sale price, subtract the discount from the original price.
Sale price = Original price – Discount
Skateboards. A store is selling their skateboards for \$57. They are mailing
out coupons for 20% off. What is the sale price without tax for this
skateboard?
20% of 57 = 0.20 x 57 = 11.40 off
S = 57 - 11.40
S = \$45.60
What is the total sale price including 5% tax?
\$45.60 x 0.05 = 2.28
\$45.60 + 2.28 = \$47.88
APPLY WHAT YOU JUST LEARNED…
Video Game. A video game is on sale for 25% off the original price. The
original price is \$48.50. What is the sale price before tax?
What is the total price including 6% sales tax?
HAPPY HALLOWEEN!!!
The Great Pumpkin Patch. Your class is having a pumpkin carving contest. Each of
the 32 students needs at least one pumpkin to carve. The farmer in the pumpkin
patch will give you a 30% discount if you purchase 40 pumpkins at \$4.45 each.
He will not charge you tax. How much will your class have to pay for the
pumpkins?
Today’s lesson is all about making
connections. Connecting the models to
number sentences. Connecting how to use
percent in real-world situations. It’s like
coming to the climax of a great story and
you will finally get to see how it plays out!!!
PRACTICE WHAT YOU HAVE LEARNED…
A book’s regular price is \$19.95. Find the cost after a 20% discount.
\$19.95 x 0.20 = \$3.99
\$19.95 - \$3.99 = \$15.96
The price of a cat toy is \$9.50. Find the cost with a sales tax of 8%.
\$9.50 x 0.08 = 0.76
\$9.50 + 0.76 = \$10.26
Compare. Your dinner bill for Monday evening is \$22.79. You leave a 20% tip
and are charged 7% sales tax. Your dinner bill for Tuesday evening is
\$23.84. You leave a 15% tip and are charged 6% sales tax. For which meal
do you pay more?
Monday \$22.79 x 0.20 = \$4.56; \$22.79 x 0.07 = \$1.60;
\$22.79 + \$4.56 + \$1.60 = \$28.95
Tuesday \$23.84 x 0.15 = \$ 3.58; \$23.84 x 0.06 = \$1.43
\$23.84 + \$3.58 + \$1.43 = \$28.85
Monday’s bill is more.
You have a coupon for an additional 25% off the price of any sale item in the
store. The store has put a watercolor kit on sale for 15% off the original
price of \$40. What is the price of the watercolor kit after both discounts?
\$40 x 0.40 = \$16.00; \$40 – 16 = \$24.00
LET’S LOOK AT THESE PROBLEMS AGAIN…
1. If you made a \$50 purchase, what is the tax (in Idaho) on your
purchase?
What would be the total cost of your purchase?
You multiplied \$50 by 0.06 and then added it back to the \$50.
2. You just bought a pizza for \$15.98 plus tax. What is the total cost of
your pizza? (Round to the nearest cent.)
You multiplied \$15.98 x 0.06 and then added it back to the \$15.98.
Can your group come up with an easier way to calculate these costs?
Perhaps there is a way to shorten the number of steps.
Would you get the same results if you multiplied the cost by 1.06?
LET’S LOOK AT THIS PROBLEM AGAIN…
Skateboards. A store is selling their skateboards for \$57. They are mailing
out coupons for 20% off. What is the sale price without tax for this
skateboard?
20% of 57 = 0.20 x 57 = 11.40 off
S = 57 - 11.40
S = \$45.60
Discuss this idea in your groups: If you are getting 20% off, how much of
the original price are you actually paying? Can your group come up with
another way to calculate this problem with less steps?
At 20% off, you are paying 80%. Try this: 57 x 0.80. Do you get the
same amount?
PRACTICE
A store is selling all flip-flops for 20% off their original price. What is the sale
price of a pair of flip-flops originally priced at \$20?
\$20 x 0.8 = \$16
If you add 6% sales tax, will you have enough money to buy the flip-flops if
you have a \$20 bill?
\$16 x 1.06 = \$16.96
A \$140 car stereo is on sale for 30% off for one day only. What is the sale price
that day? What is the total cost with 5% sales tax?
\$140 x 0.70 = \$98; \$98 x 1.05 = \$102.90
A \$750 sofa is now on sale for 40% off. Find the sale price of the sofa. Then
find the total cost including 6% sales tax.
\$750 x 0.60 = \$450; \$450 x 1.06 = \$477.00
RESOURCES
Red Book lesson 8.7 pages 406 – 409.
Blue Book lesson 9.7 pages 450 – 453.