Question

25% of what number is 21?

Answer 1

Let the unknown number be x.

25% of x is 21

25% * x = 21

0.25 * x = 21

0.25x = 21

0.25x/0.25 = 21/0.25

x = 84

Answer: The number is 84.

Answer 2

Hey there! :D

25% represents a quarter of a number. 

If 21 is a quarter of a number, multiply it by 4. 

21*4= 84

21 is 25% of 84. 

I hope this helps!
~kaikers