Question

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

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