List price from the discounted price

Statement

A tablet is sold for $357\ \text{€}$ after a $15\%$ discount on the list price. What was the list price?

Solution

If $L$ is the list price, the discounted price is $L\cdot(1 - 0{.}15) = 0{.}85\,L$. $0{.}85\,L = 357 \ \Rightarrow\ L = \frac{357}{0{.}85} = \boxed{420\ \text{€}}.$