Year 12s: what will be the first way you research your future options? >>

tsa oxford 2013 thinking skills assesmnt

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 herfriends she gives them a 10% discount on the normal sale price.

What do herfriends have to pay for one of Marilyn's cakes?

A £3.42
B £4.10
C £4.29
D £4.55
E £4.88

how is the answer b?