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 $19.50. The oil change for the other car required 7 quarts of oil and cost $22.00. How much is the labor fee and how much is each quart of oil?

Answer 1

quart of oil = $1.25

labour = $13.25

Explanation:

let x = cost of each quart of oil

y = flat fee for labour

two equations can be formed from the question

5x + y = 19.50 equation 1

7x + y = 22 equation 2

subtract equation 1 from 2

2x = 2.5

divide both sides by 2

x = 1.25

substitute for x in equation 1

5(1.25) + y = 19.50

y = 19.50 - 6.25

y = $13.25