30 is 20% of 150
Working out percentage problems of the form "30 is 20 percent of what number?"
We have, 20% × x = 30
or,
20/100 × x = 30
Multiplying both sides by 100 and dividing both sides by 20,
we have x = 30 × 100/20
x = 150
If you are using a calculator, simply enter 30×100÷20, which will give you the answer.