Question

2. It takes Jacob 30 minutes to wash the car by himself if

takes Malochi 25 minutes to wash the car by himself if
they work together, how long would it take for them to
wash the car together?

Answer 1

Let x represent the number of hours that he spent washing cars.

Let y represent the number of hours that he spent landscaping.

In a week, he can work no more than 19 total hours. This means that

x + y ≤ 19- - - - - - - - - - - -1

Jacob is working two summer jobs, making $10 per hour washing cars and making $8 per hour landscaping. He must earn at least $170. This means that

10x + 8y ≥ 170 - - - - - - - - - -2

If Jacob worked 4 hours landscaping, it means that

x + 4 ≤ 19 x ≤ 19 - 4 x ≤ 15

Also, 10x + 8 × 4 ≥ 170 10x + 32 ≥ 170

10x ≥ 170 - 32 10x ≥ 138

10x ≥ 138/10 x ≥ 13.8

The minimum number of hours is 14