```3-7 Adding and Subtracting Fractions
Warm Up
Lesson Presentation
Lesson Quizzes
Learn to add and subtract fractions.
Fractions with Like Denominators
5+1
8 8
5+ 1 = 5 + 1
8
8 8
=6= 3
4
8
the denominator.
Simplify.
Fractions with Like Denominators
Subtract. Write the answer in simplest form.
9
4
–
11 11
4 = 9–4
9
–
11
11
11
= 5
11
Subtract the numerators and
keep the denominator.
The answer is in the simplest
form.
Check It Out: Example 1A
5+1
6 6
5+ 1 = 5 + 1
6
6 6
=6= 1
6
the denominator.
Simplify.
Check It Out: Example 1B
Subtract. Write the answer in simplest form.
7
4
–
10 10
4 = 7–4
7
–
10
10
10
= 3
10
Subtract the numerators and
keep the denominator.
The answer is in the simplest
form.
3
5
Kevin is 48 inches tall. His brother Keith is 5
8
8
inches taller. How tall is Keith ?
483 + 5 5 = 53+ 8
8
8
8
= 53 + 1
54 inches tall.
Rewrite8 as 1.
8
A mixed number is the sum of an integer
and a fraction: 3 4 = 3 + 4 .
5
5
Check It Out: Example 1
2
Alvin weighs 72 3 lbs. His baby brother weighs
15 1 lbs. How much do they weigh together?
3
72 2 + 15 1 = 87 + 3
3
3
3
= 87 + 1
Rewrite3 as 1.
3
Together they weigh 88 pounds.
Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems
3-8 Adding and Subtracting Mixed Numbers
9
2 + 12 2
3
3
9 2 + 12 2 = 21 +
3
3
4
3
Rewrite the improper
1
= 21 + 1
3 fraction as a mixed
1
= 22
3
Add the fractions first in case an improper
fraction needs to be rewritten.
Lesson Quiz
simplest form.
3 5
2
1
1. 5 – 3
2. +
8 8
7 7
7
3. 5 + 1
12 2
11
12
4. 1 – 1
3 12
1
4
5. You need a nail to go through a 7 -inch door
8
1
and extend an extra inch. How long should
4
the nail be?
11 in.
8
Lesson Quiz for Student Response Systems
4+5
9
9
A. 0
C. 1
9
B. 1
2
D. 1
Lesson Quiz for Student Response Systems
form.
9– 5
11 11
3
11
A.
4
11
C.
B.
14
3
or 1
11
11
4
D. 1
11
Lesson Quiz for Student Response Systems
3+1
8
3
A.
4
11
C.
17
24
B.
3
11
D.
24
or 1 7
17
17
Lesson Quiz for Student Response Systems
form.
5 – 1
12 5
A.
4
7
C.
13
60
B.
6
7
D.
60
8
or 4
13
13
Lesson Quiz for Student Response Systems
8
pounds of fruits to make a
9
5
pudding. Sam has
pounds of fruits. How
12
much more does he need to make the
pudding?
5. You need
17
A.
lb
24
B.
19
lb
24
17
C.
lb
36
D.
19
lb
36
```