Let us assume the weight of grapefruit = x pounds
Weight of the apples = 1 5/8 pounds
= 13/8 pounds
Weight of the bananas = 3/16 pounds
The total weight of her purchase = 7 1/2 pounds
= 15/2 pounds
Then we get the equation as
x + 13/8 + 3/16 = 15/2
16x + 26 + 3 = 16 * (15/2)
16x + 29 = 8 * 15
16x + 29 = 120
16x = 120 - 29
16x = 91
x = 91/16
So the weight of the grapefruit is 91/16 pounds. It can also be written
as 5 11/16 pounds