Question 56991
Hello,


If 18 is 20% of a certain x, then that means that: 20*x /100 = 18

You only take 20% of x, that's why you multiply x by 20/100 (it makes x smaller)

So: 20*x/100 = 18

Multiply both sides by 100 to obtain:  20*x = 1800

Divide by 20 at both sides:

x = 1800/20 = 90

This means that 20 % of 90  = 18