Mr. Davis wants to rent a truck for a move across the country. The cost (c ) of a 30-foot truck can be represented by the equation c = 60d, where d represents the number of days. The cost of renting a 24-foot truck is represented by the graph below.
How much more would Mr. Davis have to pay if he rents the 30-foot truck for 5 days rather than the 24-foot truck for 5 days?