We are given two coupons A and B. Coupon A gives a 60% discount on a $87 item. Let's calculate the amount to pay by subtracting 60% of 87. We do that by multiplying 87 by 60/100, like this:
Now we subtract this from the initial price, like this:
therefore, using coupon A she must pay $34.8
For coupon B there's a rebate of $55. We calculate the amount to pay by subtracting 55 to the total price of 87, like this:
Therefore, using coupon B she must pay $32.
Coupon B gives the lowest price, the price of coupon B compared to coupon A is calculated by subtracting both prices:
Therefore, with coupon B she pays $2.8 less than the price with coupon A.