Question

15% OFF!

Gabe wants to buy a dog collar. The sale price is $3.91. What was the original price?
$

Answer 1

the original price was really "x", which oddly enough is the 100%, but today the collar is on sale at 15% off, that means the sale price is 100% - 15% = 85% of the original price, and we happen to know that's $3.91, so

`\begin{array}{ccll} Amount&\%\\ \cline{1-2} x & 100\\ 3.91& 85 \end{array} \implies \cfrac{x}{3.91}~~=~~\cfrac{100}{85} \\\\\\ \cfrac{x}{3.91} ~~=~~ \cfrac{20}{17}\implies 17x=78.2\implies x=\cfrac{78.2}{17}\implies x=4.6`