Answer:
The more expensive book cost $90, the other two combined cost $60.
Step-by-step explanation:
x = cost of more expensive book
y = subtotal cost of the other books
x = 50% more than y, so x = 1.50y = 1.5y
x + y = total cost = $150
1.5y + y = 150
y = 150/2.5 = 60
x = 1.5y = 1.5(60) = 90
