Question

Betty makes pies to make 6 pies, she uses 7 and 1/2 cups of flour. How many cups of flour are needed to make 9 pies?

Answer 1

let's firstly convert the mixed fraction to improper fraction.

`\bf \stackrel{mixed}{7(1)/(2)}\implies \cfrac{7\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{15}{2}} \\\\\\ \begin{array}{ccll} pies&\stackrel{flour}{cups}\\ \cline{1-2}\\ 6&(15)/(2)\\ 9&x \end{array}\implies \cfrac{6}{9}=\cfrac{~~(15)/(2)~~}{x}\implies \cfrac{2}{3}=\cfrac{~~(15)/(2)~~}{(x)/(1)}\implies \cfrac{2}{3}=\cfrac{15}{2}\cdot \cfrac{1}{x} \\\\\\ \cfrac{2}{3}=\cfrac{15}{2x}\implies 4x=45\implies \cfrac{4}{45}=x`