what is the y intercept of (-9,45) and (9,-45)?
m = (y2 - y1) / (x2 - x1)
m = (-45 - 45) / (9 - (-9))
m = -90 / 18
m = -5
m = mx + b
b = y - mx
b = 45 - (-5)(-9)
b = 45 - 45
b = 0
The y-intercept is 0. The graph of this line passes
through the origin, (0, 0)