21 is 12% of what number?

If you would like to know 12% of what number is 21, you can calculate this using the following steps:

12% of what number is 21
12% of x is 21
12% * x = 21
12/100 * x = 21    /*100/12
x = 21 * 100 / 12
x = 175

Result: 12% of 175 is 21.

Iam thinking the answer is a.) knew