Luana

Luana is making a recipe that uses 2 7/8 cups of sugar. She has 1 1/4 cups sugar in her sugar bowl and 7 1/2 cups in the canister. How many cups of sugar will Luana have left after she makes her recipe?

Correct answer:

x =  5 ⁷⁄₈ = 47/8 c

Step-by-step explanation:

$$\begin{gathered} a=1\frac{1}{4}=1+\frac{1}{4}=\frac{1\cdot 4+1}{4}=\frac{4+1}{4}=\frac{5}{4}=1.25\text{c} \\ b=7\frac{1}{2}=7+\frac{1}{2}=\frac{7\cdot 2+1}{2}=\frac{14+1}{2}=\frac{15}{2}=7.5\text{c} \\ c=2\frac{7}{8}=2+\frac{7}{8}=\frac{2\cdot 8+7}{8}=\frac{16+7}{8}=\frac{23}{8}=2.875\text{c} \\ x=a+b-c=\frac{5}{4}+\frac{15}{2}-\frac{23}{8}=\frac{10}{8}+\frac{60}{8}-\frac{23}{8}=\frac{10+60-23}{8}=\frac{47}{8}=\frac{47}{8}\text{c}=5\frac{7}{8}\text{c}=5.875\text{c} \end{gathered}$$

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