Question

Books are on sale for25% off. The discountis $4. What is theregular price of thebook?

Answer 1

We know that the value of the discount is equal to $4 and that it represents 25% of the original value. To find the regular price we can apply a rule of three in such a way that $4 is related to 25% in the same proportion that "x" is related to 100%, where "x" is the regular price of the book. We have:

`(4)/(x)=(25)/(100)`

Doing the cross product we have:

`\begin{gathered} 25\cdot x=4\cdot100 \\ x=(4\cdot100)/(25)=16 \end{gathered}`

The regular price of the book is $16.