First we have to find the slope formula with the points (0,-7) and (-6,-2). Doing so, we have:

We can see in the graph that the y-intercept is at (0,-7), therefore the equation would be:
y= mx + b (m:slope, b: y-intercept)
y= (-5/6)x - 7 (Replacing)
The answer is y= (-5/6)x - 7