Answer:
Maximum number of pounds of grapes: 9
Explanation:
If you spend all the money, $18, in grapes then you will maximize the number of pounds of grapes you can buy. That means, to solve the equation for y, the number of pounds of grapes, with x = 0 (the number of pounds of oranges):
1.5*0 + 2*y = 18
y = 18/2
y = 9