Paul and Jack are 2 mechanics who work 8 hours per day changing oil in cars at The Oil Spot. If Paul can change oil in 2 cars per hour, and Jack can change oil in 3 cars per hour. What is the least number of cars per work day the 2 men can finish?
Choices.
A) 50  B) 40  C) 35  D) 10  E) 90
The proportion equation can be used. Let x = number cars and C = least number of cars per day the 2 men can finish (C = x/(8 hours), P = cars per hour Paul can change, and J = cars per hour Jack can change. Note: 8 hours = a work day   P + J = C   (2 cars/hour) + (3 cars/hour) = x/(8 hours)   Proportion: 2/1 + 3/1/ = x/300   x = 8(2 + 3) = 40. At least 40 cars per work day.   Answer is 40
<result>B</result>
Paul and Jack are 2 mechanics who work 8 hours per day changing oil in cars at The Oil Spot. If Paul can change oil in 2 cars per hour, and Jack can change oil in 3 cars per hour. What is the least number of cars per work day the 2 men can finish?