
First, convert the percentage to a decimal. You can do this by moving the decimal place two places to the left.

Now, simply multiply that decimal by
using a calculator.

What 2 numbers multiply to get 40 and add to get -14
-10 and -4
(x-4)(x-10)=0
set to zero
x-4=0
x=4
x-10=0
x=10
x=4 and 10