21 is 75% of what amount

21 is 75% of 28. You already know that to make 100, you need 4 25's. 75 is three 25's. You take 21 and divide it by three to get seven. Then you take your past knowledge and multiply 7 by 4 and get 28.

In the given question it is required to find an unknown amount from all the details given in the question. It is given that 21 is the 75% of the unknown number.

Let us consider the amount = x

Then we can write the equation as

75x/100 = 21

75x = 21 * 100

75x = 2100

x = 2100/75

= 28

So the correct amount is 28 ... I hope to have made the procedure clear for finding the solutions of such problems.