Let h be the numbers of hours, f be the one-time fee and c the cost charged. The equation is

Since you pay $15 per four, plus the fee. We can solve this equation for the fee:

If we plug c=195 and h=9, we have

9.) 3
10.) 1
11.) x-axis
12.) 4
13.) y-axis
The slope is always change in y value over change in x value so if you pick any 2 points on the line you’ll see that the slope is 30/40 and that simplified is 3/4 so the slop is 3/4
Do you want this simplified?