y = mx + c
m = y2 - y1/ x2 - x1
Let’s use the points (-4, 9) and (5, -9)
m = -9-9/5-(-4)
= -18/9
= -2
y = -2x + c
-9 = (-2 x 5) + c
-9 = -10 + c
-9 + 10 = c
c = 1
(Or you could just get it from the graph, c is the y-intercept so it’s where the graph intersects with y-axis when x = 0)
y = -2x + 1