Question

A shirt is on sale for 40% off. The sale price is $12. What was the original price? What was the amount of the discount?

Answer 1

x = original price, or 100%

we know then that it original costs "x", which is the 100%, however is discounted by 40%, so the discounted price is really then 100% - 40% = 60%, and we know that that 60% is $12.

if 60% of the original price is $12, what is "x", the 100%?

$\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 12&60 \end{array}\implies \cfrac{x}{12}=\cfrac{100}{60}\implies \cfrac{x}{12}=\cfrac{5}{3}\implies 3x=60 \\\\\\ x=\cfrac{60}{3}\implies x=20 ~\hfill \stackrel{\textit{amount of the discount}}{20-12\implies 8}\\ ~\hspace{34em}$