Question

Use the appropriate form of the percentage formula.30% of what number is 21?

Answer 1

If 30% of a number x is equal to 21, then x is to 100% as 21 is to 30%:

$\frac{x}{100}=\frac{21}{30}$

Solve for x:

$x=\frac{21}{30}\times100=70$

Then, 30% of 70 is 21.

Therefore, the answer is 70.