Question

A 50 coat is put on sale for 35 What percent is the decrease?

Answer 1

so the coat went down from 50 to 35, namely 15.

if we take 50 to be the 100%, what is 15 off of it in percentage?

$\bf \begin{array}{ccll} aount&\%\\ \cline{1-2} 50&100\\ 15&x \end{array}\implies \cfrac{50}{15}=\cfrac{100}{x}\implies \cfrac{10}{3}=\cfrac{100}{x} \\\\\\ 10x=300\implies x=\cfrac{300}{10}\implies x=30$