If 1/3 of the oranges were spoiled and you threw away 4 oranges, there would be a total of 12 oranges.
4 x 3 = 12
If 1/4 of the grapefruits were spoiled and you threw away 7 grapefruits, there would be a total of 28 grapefruits.
7 x 4 = 28
Add the total amount of oranges to the total amount of grapefruits and you get how many pieces of fruit were in the basket.
12 + 28 = 40
