Jeff is making cookies for his school. He needs 150 cookies. One recipe makes 60 cookies and uses 1.5 cups of butter. How many tablespoons of butter will be needed to make 150 cookies? (1 cup = 16 Tbsp.) Show how to use unit fractions to solve this problem.

Answer

Since one recipe makes 60 cookies, we can write the unit fraction LaTeX: \frac{1\text{ recipe}}{60\text{ cookies}}1  recipe 60  cookies. Since one recipe uses 1.5 cups of butter, we can write the unit fraction LaTeX: \frac{1.5\text{ cups butter}}{1\text{ recipe}}1.5  cups butter 1  recipe. And since 1 cup = 16 Tbsp., we can write the unit fraction LaTeX: \frac{16\text{ Tbsp}}{1\text{ cup}}16  Tbsp 1  cup.

Multiply:

LaTeX: \frac{150\text{ cookies}}{1} \cdot \frac{1\text{ recipe}}{60\text{ cookies}} \cdot \frac{1.5\text{ cups butter}}{1\text{ recipe}} \cdot \frac{16\text{ Tbsp}}{1\text{ cup}}150  cookies 1 ⋅ 1  recipe 60  cookies ⋅ 1.5  cups butter 1  recipe ⋅ 16  Tbsp 1  cup

= LaTeX: \frac{150(1)(1.5)(16)}{1(60)(1)(1)} 150 ( 1 ) ( 1.5 ) ( 16 ) 1 ( 60 ) ( 1 ) ( 1 )

= 60 Tbsp. butter

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