Respuesta :
Use the point-slope form. y-y₁= m(x-x₁). m stands for the slope. Do rise over run for the slope, which is (9-0)/(-3-0)= 9/-3 = -3. Use either (-3,9) or (0,0) as your (x₁,y₁). Using (0,0) is faster, so the equation is y=-3x