you can manipulate the number to make them easier to handle
3 and 1/3 times 12=36+4=40
6 and 1/4 times 12=72+3=75
so is 40=100% then wha is 75
40 and 75
divide by 2
20 and 37.5
multiply by 5
100 and 187.5
100=100% and 187.5=187.5%
187.5-100=87.5%
87.5% increase