I know that the other guy answered your question, but didn't explain. So I will explain why it is 75 %. 28 matches is the base of the question. So it will go in the denominator. 21 is the part, and goes in the numerator. So you get 21/28. If you divide both sides by 7, you get 3/4. Now do 3 divided by 4 to get .75. Move the decimal 2 places to the right to get 75 %.