Question

18% of 90 is what number?

Answer 1

90/x=100/18
(90/x)*x=(100/18)*x       -  multiply both sides of the equation by x
90=5.55555555556*x       - divide both sides of the equation by (5.55555555556) to get x
90/5.55555555556=x 
16.2=x 
x=16.2
18% of 90=16.2

Answer 2

The answer to you problem is 16.2, the equation you needed was, 90/0.18