The one thing that changes in the problem is the milk. It goes from 8 oz. to 12 oz., so we are going to use the oz count to determine the amount of espresso. Since the amount of milk rose, so is the amount of espresso. Now, you take the larger number and divide it by the smaller number (12 / 8 = 1.5). This answer will tell you by what multiple it increased by. Once you have the multiple it increased by, you multiply that answer (1.5) by the other unknown changing number, so 1.5 x 1.5. Do this and you get 2.5.
