Question

11. The price of a sweater changed from $20 to $12. By what percentage was the price of the sweater

changed?
The price of the sweater decreased by __ %

Answer 1

well, the change was 8 bucks.

if we take 20 to be the 100%, what is 8 off of it in percentage?

`\begin{array}{ccll} amount&\%\\ \cline{1-2} 20 & 100\\ 8& x \end{array} \implies \cfrac{20}{8}~~=~~\cfrac{100}{x} \\\\\\ \cfrac{5}{2}=\cfrac{100}{x}\implies 5x=200\implies x=\cfrac{200}{5}\implies x=40`