Mary buys 3 classical CDs and 2 travel books. When Mary buys 3 classical CDs and 2 travel books she spends $50. Mary maximizes her utility when she spends all of her money and the marginal utility per dollar from classical CDs and travel books is the same. When Mary buys 3 classical CDs her marginal utility per dollar spent is 0.8 units per dollar and when Mary buys 2 travel books her marginal utility per dollar spent is 0.8 units per dollar