Unit 3 Lesson 13: Fraction Operations

How do you add or subtract like fractions such as 2/7 + 3/7 and 7/8 - 5/8?

• Find equivalent fractions with the same denominator.

• Multiply the denominators and multiply the numerators.

• Multiply the whole number by the denominator of the fraction.

• Multiply the fraction by 1 over the whole number.

• Add or subtract the numerators.

How do you add or subtract two unlike fractions, such as 1/3 + 2/7?

• Find equivalent fractions with the same denominator.

• Multiply the denominators and multiply the numerators.

• Multiply the whole number by the denominator of the fraction.

• Multiply the fraction by 1 over the whole number.

• Add or subtract the numerators.

How do you multiply two fractions, such as 3/4 * 2/5?

• Find equivalent fractions with the same denominator.

• Multiply the denominators and multiply the numerators.

• Multiply the whole number by the denominator of the fraction.

• Multiply the fraction by 1 over the whole number.

• Add or subtract the numerators.

How do you divide a whole number by a unit fraction, such as 4 $\div$  1/3?

• Find equivalent fractions with the same denominator.

• Multiply the denominators and multiply the numerators.

• Multiply the whole number by the denominator of the fraction.

• Multiply the fraction by 1 over the whole number.

• Add or subtract the numerators.

How do you divide a unit fraction by a whole number, such as 1/3  $\div$  5?

• Find equivalent fractions with the same denominator.

• Multiply the denominators and multiply the numerators.

• Multiply the whole number by the denominator of the fraction.

• Multiply the fraction by 1 over the whole number.

• Add or subtract the numerators.

Decide which operation to use, then solve. Hala can ride her bike 7 1/2 miles in an hour. How far will she ride in 3 hours?

• Multiplication: 21 1/2

• Multiplication: 22 1/2

• Division: 3

• Addition: 10 1/2

Eryn's pet rabbit eats  $\frac{1}{12}$   pound of food every day. If Eryn buys rabbit food in 5 pound bags, how many days does one bag of rabbit food last?

• Subtraction:   4  $\frac{11}{12}$  days

• Subtraction:  $\frac{1}{12}$  days

• Division:   60 days

• Addition:   5 $\frac{1}{12}$  days

Jonathon can throw a baseball 10  $\frac{1}{3}$  yards. His brother Joey can trhow a baseball 13  $\frac{1}{2}$  yards. How much farther can Joey throw?

• Subtraction:   2  $\frac{3}{4}$  yards

• Subtraction:   3   $\frac{1}{6}$  yards

• Division:  1  $\frac{19}{62}$  yards

• Addition:   23  $\frac{5}{6}$  yards

Kim bought  $\frac{3}{8}$  pound of sunflower sees and  $\frac{3}{16}$  pound thistle seed for her bird feeder. How much seed did she buy in all?

• Addition:   $\frac{6}{24}$  pound

• Addition:   $\frac{9}{16}$  pound

• Multiplication:    $\frac{9}{128}$  pound

• Subtraction:   $\frac{0}{8}$  pound

Marcus studies for 9 hours each week. His friend Luis spends 5/6 as much time studying. Who studies more? How much time does Luis spend studying?

• Marcus: about one hour

• Luis: 9 $\frac{5}{6}$ hours

• Marcus: 7 $\frac{1}{2}$ hours

• Luis: about 18 hours