A car parking charges n dollars for the first hour, and m pence for every additional hour. What amount it will charge if a car stayed for 5 hours?

(A) n + 5m
(B) n + 4m
(C) m + 4n
(D) m + 5n

The answer is: (B) n + 4m
Solution
First hour charges = n, remaining 4 hour charges = 4m. Total charges = n + 4m