Question

15 is 30% of what number?

Answer 1

If 15 is 30%, then 1% is 15/30=0.5
since 1% is 0.5, then 100% (the number) is 
0.5x 100= 50
:)

Answer 2

15 is 30% of 50 

Change the percentage to a decimal by dividing it over 100:
$\frac{30}{100} = 0.3$

Divide 15 over 0.3:
$\frac{15}{0.3} = 50$