13 Every Thursday, Marilyn spends 10 hours making 60 cakes to sell at her local market. The cost of the ingredients to make each cake is 1.60 and Marilyn charges 6 an hour for her time. She usually sets the sale price for a cake at 75% more than the total costs of making it. However, when she sells to her friends she gives them a 10% discount on the normal sale price. What do her friends have to pay for one of Marilyn's cakes? A 3.42 B 4.10 C 4.29 D 4.55 E 4.88