Use the given information as (x, y) points. You have (1, 34) (2, 50) (3, 66) (4, 82) The difference between renting for 1 day and 2 days is 50 - 34 = 16. The difference between renting for 2 days and 3 days is 66 - 50 = 16 The difference between renting for 3 days and 4 days is 82 - 66 = 16 For each day you rent you pay $16. Now look at renting for 1 day. The rental for 1 day is $16, but for 1 day you pay $34. $34 - $16 = $18 There is an extra $18 in the rental for every day. The $18 is fixed. That means, to rent a truck, you must pay a fixed amount of $18 plus $16 per day.
total cost = daily cost + fixed cost total cost = 16d + 16 c = 16d + 18
