Question

Mary is making Magic Marshmellow cake . The recipe calls for 3/4 cup of milk and 2 eggs per serving. The wants to make enough cake for 20 people . How much milk will Mary need?

Answer 1

$\bf \begin{array}{ccllll} \textit{cups of milk}&serving\\ -----&-----\\ \frac{3}{4}&1\\ x&20 \end{array}\implies \cfrac{\frac{3}{4}}{x}=\cfrac{1}{20}\implies \cfrac{\frac{3}{4}}{\frac{x}{1}}=\cfrac{1}{20} \\\\\\ \cfrac{3}{4}\cdot \cfrac{1}{x}=\cfrac{1}{20}\implies \cfrac{3}{4x}=\cfrac{1}{20}\implies 3\cdot 20=1\cdot 4x\implies \cfrac{3\cdot 20}{4}=x$

and surely you know how much that is.