Slope intercept form is y=mx+b where b is the y intercept and m is the slope. In this particular example, the y intercept is at (0,0), the origin, so b=0. y=mx+0 or just y=mx. Now, to determine the slope, we must look at the graph. It appears the graph intersects the point (-10, 60) as well as the point (0,0). Other than just calculating it quickly in your head, the way to get slope from that is y1-y2/x1-x2. Setting that up, 60-0/-10-0, which is 60/-10, which is equal to -6. Put that into the equation and you get y=-6x