Cups of punch

Cyka made 6 19/20 cups of punch with two different types of juice in it. If the punch had 4 1/5 cups of one type of juice, how many cups of the other type of juice did it have?

Correct answer:

b =  2 ³⁄₄ = 11/4

Step-by-step explanation:

$$\begin{gathered} t=6\frac{19}{20}=6+\frac{19}{20}=\frac{6\cdot 20+19}{20}=\frac{120+19}{20}=\frac{139}{20}=6\frac{19}{20}=6.95 \\ a=4\frac{1}{5}=4+\frac{1}{5}=\frac{4\cdot 5+1}{5}=\frac{20+1}{5}=\frac{21}{5}=4\frac{1}{5}=4.2 \\ b=t-a=\frac{139}{20}-\frac{21}{5}=\frac{139}{20}-\frac{84}{20}=\frac{139-84}{20}=\frac{55}{20}=\frac{11}{4}=2\frac{3}{4}=2.75 \end{gathered}$$

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