Use 2 points on the line to find the slope.
Slope = change in y / change in x
The two points used: (-2,5) and ( 1,-10)
slope = (-10 -5) /(1- -2) = -15/3 = -5
the y intercept is where the line is at in the y direction when it crosses the x axis at 0.
the y intercept is -5
The equation is y = -5x -5