A mechanic charges a very reasonable $ 40 $ 40 per hour to work on cars. For a particular repair, $ 120 $ 120 worth of parts are required. Let x x represent the number of hours that the mechanic works on the car, and let y y represent the total cost of the repair: 1 2 3 4 5 6 7 8 -1 -2 40 80 120 160 200 240 280 320 360 -40