Question

10 is 40% percent of what

Answer 1

10 is 40% percent of what 400 maybe 

Answer 2

Hello there! 
10 is 40% percent of what?
Well.....
100%/x%=40/10
First,  multiply both sides of your equation by x:
(100/x)*x=(40/10)*x
Second, you need to divide both sides of your equation by (4) in order to get x:100=4*x
100/4=x 
Answer:
x=25
Therefore, 10 is 25% of 40

Good luck with your studies, I hope this helps~!