Answer:
He wants to win $300.
he mows the lawn y times, and he works x hours in his part time job,
Then we will have the equation:
y*$9 = amount that he wins by mowing the lawn
x*$7.25 = amount that he wins in his part time job.
Adding those, we must get $300.
y*$9 + x*$7.25 = $300.
We can isolate y and get
y = ($300 - x*$7.25)/$9 = (300/9) + x*(7.25/9)
This is the boundary line that he should use in the graph.
now, with if he works x = n hours, he can input that in this equation and find the number of times that he must mow the lawn in order to reach to the desired $300.
The graph of the line is below.
Any point in that line (in the first quadrant) is a possible way for Jacob to make the $300
Outside of the first quadrant this equation does not work, because it has negative values of y or x, and we can not have things like "negative hours of work", so we only look at the first quadrant.
