Answer:
The slope is -3/1, and is in the simplest form. Thus, your equation is y=-3/1x+7.
Explanation:
Why is this the case? Well we can do what M is, which is Y2-Y1/X2-X1. Lets pick a point on the graph, and the easiest point, the Y-Intercept, which is (0,7) and another one, which is (1,4). Now plug it into that formula, 4-7/1-0= -3/1. Take a look at the photo to see how the graph is made by just looking at it, the red is the rise and run.