Well you pay 50$ for the first one, for the second one your paying 12.50 less and for the third one your paying 25 less, if you add them together you get 112.5, it originally would have costed 150, so you would subtract 150 - 112.5, which equals 37.5 so she saved 37.5 dollars on the rings(Here is a quick simple short way to do it.. she payed 12.50 less and 25 less that added together is 37.5)
