These equations are in point-slope forma:-
y - y1 = m(x - x1) where m = slope and (x1, y1) is a point on the line.
In our question we have x1 = -9 , y1 = -3 and m = -6 so plugging in these values we have:-
y - (-3) = -6(x - (-9))
y + 3 = -6(x + 9) is the answer
