Question

It takes ¾ of a cup of flour to make 6 pancakes. You have many visitors one weekend and determine that you must make 72 pancakes to feed everyone. How many cups of flour will you need?

Answer 1

`\bf \begin{array}{ccllll} flour&pancakes\\ \textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\ (3)/(4)&6\\\\ x&72 \end{array}\implies \cfrac{(3)/(4)}{x}=\cfrac{6}{72}\implies \cfrac{(3)/(4)}{(x)/(1)}=\cfrac{6}{72} \\\\\\ \cfrac{3}{4}\cdot \cfrac{1}{x}=\cfrac{6}{72}\implies \cfrac{3}{4x}= \cfrac{6}{72}\implies 72\cdot 3=6\cdot 4x\implies 216=24x \\\\\\ \cfrac{216}{24}=x`

and surely you know how much that is