1) To find the solution, find the point where the two lines intersect
The graph isn't that clear, so round the numbers to an integer value, the point to where the point is the closest.
(2, 4)
2. A. Since the cost are the same and the solution is (8, 120) it will cost you the same money to rent a boat for 8 hours. You will pay $120 for both.
3. To find the solution, find the point where the line a and b intersect, which is (3,0) C.
Hope this helps.