Help: 20% of 320

The answer would be 64. 

320/x=100/20
(320/x)*x=(100/20)*x       - we multiply both sides of the equation by x
320=5*x       - we divide both sides of the equation by (5) to get x
320/5=x 
64=x 
x=64

Hope this helps! :)

-Hayley