The lines x = 0, y = 2x - 5, and y = mx + 9 form a right triangle. find two possible values of m.

In order for y = mx + 9 to form a right triangle it should be perpendicular to either x = 0 or y = 2x-5
For it to be perpendicular to x = 0 (a vertical line), it has to be horizontal constant, so m1 = 0
For it to be perpendicular to y=2x-5, m should be such that m * 2 = (-1), so m = -0.5

That said, two possible values of m are: 0 and -0.5