Set up a proportion. You know that 20%= 20/100 and 15=20%.
15/x= 20/100
Cross multiplication method:
15*100=1500
1500/20=75
x=75
You can also find that the numerator to denominator ratio is 1:5 and find the answer by multiplying the known numerator, 15, by 5 to get 75.
Final answer: 75