Answer:
5 grapes
Explanation:
You can use a proportion.
12 grapes is to 90$ as x grapes is to 40$
12/90 = x/40
90x = 12 * 40
9x = 12 * 4
9x = 48
x = 5.33
Since you cannot buy 1/3 of a grape, you need to round down to the nearest whole number.
Answer: 5 grapes