Let us assume the percentage = x%
Then
75 * x% = 27
75x/100 = 27
3x/4 = 27
3x = 27 * 4
3x = 108
x = 108/3
= 36 percent
So 27 is 36 percent of 75. I hope the procedure for solving this kind of problems is absolutely clear to you. You can always use this method for solving similar problems and hopefully you will not require any help from outside. Just keep a cool brain while doing the calculation part.