So we want to know the number from which we take 75% and get 27. If the number we are looking for is x, then the equation to find that x would be: (75/100)*x=27 which says seventy five percent out of x is equal 27. So, x=(27*100)/75. And finally, x= 2700/75=36. So, 75% out of 36 is 27.