Well the way to solve this problem would be to put up a proportional relationship. you would put 36% over 100 and then put an equal sigh with the 84 as the denominator. (36%/100 = /84) now all thats left to do is find the number that should go over the 84. to find this you would cross multiply and divide. so it would be... 84 x 36 divided by 100. and that equals 30.24.
hope this helped and could you give me a thanks? :D