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3-7 Adding and Subtracting Fractions Warm Up Lesson Presentation Lesson Quizzes 3-7 Adding and Subtracting Fractions Learn to add and subtract fractions. 3-7 Adding and Subtracting Fractions Additional Example 1A: Adding or Subtracting Fractions with Like Denominators Add. Write the answer in simplest form. 5+1 8 8 5+ 1 = 5 + 1 8 8 8 =6= 3 4 8 Add the numerators and keep the denominator. Simplify. 3-7 Adding and Subtracting Fractions Additional Example 1B: Adding or Subtracting 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. 3-7 Adding and Subtracting Fractions Check It Out: Example 1A Add. Write the answer in simplest form. 5+1 6 6 5+ 1 = 5 + 1 6 6 6 =6= 1 6 Add the numerators and keep the denominator. Simplify. 3-7 Adding and Subtracting Fractions 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. 3-7 Adding and Subtracting Fractions Additional Example 1: Measurement Application 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. Add the integers and add the fractions. Rewrite8 as 1. 8 Helpful Hint A mixed number is the sum of an integer and a fraction: 3 4 = 3 + 4 . 5 5 3-7 Adding and Subtracting Fractions 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 Add the integers and add the fractions. Rewrite3 as 1. 3 Together they weigh 88 pounds. 3-7 Adding and Subtracting Fractions Lesson Quizzes Standard Lesson Quiz Lesson Quiz for Student Response Systems 3-8 Adding and Subtracting Mixed Numbers Additional Example 2A: Adding Mixed Numbers Add. Write the answer in simplest form. 9 2 + 12 2 3 3 9 2 + 12 2 = 21 + 3 3 4 3 Add the fractions and then add the integers. Rewrite the improper 1 = 21 + 1 3 fraction as a mixed 1 number. Add = 22 3 Helpful Hint Add the fractions first in case an improper fraction needs to be rewritten. 3-7 Adding and Subtracting Fractions Lesson Quiz Add or subtract. Write each answer in 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 3-7 Adding and Subtracting Fractions Lesson Quiz for Student Response Systems 1. Add. Write your answer in simplest form. 4+5 9 9 A. 0 C. 1 9 B. 1 2 D. 1 3-7 Adding and Subtracting Fractions Lesson Quiz for Student Response Systems 2. Subtract. Write your answer in simplest form. 9– 5 11 11 3 11 A. 4 11 C. B. 14 3 or 1 11 11 4 D. 1 11 3-7 Adding and Subtracting Fractions Lesson Quiz for Student Response Systems 3. Add. Write your answer in simplest form. 3+1 8 3 A. 4 11 C. 17 24 B. 3 11 D. 24 or 1 7 17 17 3-7 Adding and Subtracting Fractions Lesson Quiz for Student Response Systems 4. Subtract. Write your answer in simplest form. 5 – 1 12 5 A. 4 7 C. 13 60 B. 6 7 D. 60 8 or 4 13 13 3-7 Adding and Subtracting Fractions 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