In fractional simplest form we would begin by dividing both by 2 (always start this way, it's easier).
72/2 = 36
100/2 = 50
Now, we have 36/50 which could also be divided by 2.
36/2 = 18
50/2 = 25
Now, we have 18/25. From here, you would look to see if either number can be simplified using a common factor. With these numbers, nothing could be further simplified, so it would stay this way. :)
