Question

Two cars got an oil change at the same auto shop. The shop charges customers for each quart of oil plus a flat fee for labor. The oil change for one car required 5 quarts of oil and cost $22.45. The oil change for the other car required 7 quarts of oil and cost $25.45. How much is the labor fee and how much is each quart of oil?

Answer 1

(5,22.45),(7,25.45)
slope = (25.45 - 22.45) / (7 - 5) = 3/2 or 1.5

y = mx + b
slope(m) = 1.5
use either of ur points...(5,22.45)...x = 5 and y = 22.45
now sub and find b
22.45 = 1.5(5) + b
22.45 = 7.5 + b
22.45 - 7.5 = b
14.95 = b

so ur equation is : y = 1.5x + 14.95.......this means that each quart of oil costs $ 1.50 and the labor fee costs $ 14.95