Use the IS over OF:IS/OF next set up a proportion: IS/OF=%/100 since 54 is before IS therefore it is the "IS". And 75 is the % .We don't know what is OF so,we replace it with "X" it will be something like this: 54/X = 75/100 and then cross multiply, 54(100)=5400 and 75(x)=75x so 5400=75x divide each side by 75 5400/75=72 and that's your answer,72.