Question

Calvin decides to take his daughter on the trip. His daughter is 7 years old. Children ages 2 – 16 get a 20% discount. If the adult fares are $42 and $30, what would Calvin’s daughter have to pay for her round-trip fare (total)? _

Answer 1

By getting a 20% discount, Calvin's daughter will have to pay only 80% or 0.80 of the adult fare. I assume that the fares given are for the to-and-fro trips and that Calvin's daughter will have to pay 80% of these fares. 
                           to:   (0.80)($42) = $33.6
                         fro:    (0.80)($30) = $24
Adding up the fares will give us an answer of $57.6. Therefore, Calvin's daughter will have to pay $57.6 for the round-trip fare.