Answer:
profit = revenue - cost
10 = 20x - (4.5 + 2.5)
10 = 20x - 7
10 + 7 = 20x
17 = 20x
17/20 = x
0.85 = x
check...
profit = revenue - cost
10 = 20(0.85) - 7
10 = 17 - 7
10 = 10 (correct)
so he would have to sell each cup at 0.85 ccents to make a profit of $ 10
