27/50=.54, so the answer is 54%

27/100, This fraction cannot be reduced because 27 and 100 have no factors in common.

If you want to know what 90 plus 20% is, then: 20%=.2, so you multiply 90 by 1.2 = 108
If you just want to know what 20% of 90 is, then you multiply 90 by .2 = 18