Answer:
15. -2 16. 0 17. undefined
Explanation:
Slope of two points can be calculated by (y change) / (x change).
(y1 - y2) / (x1 - x2)
15) (1-5) / (4-2) = -2
16) (6-6) / (1-10) = 0 since y change is 0.
17) (-5-3) / (4-4) = undefined since x change is 0 but you cannot devide by 0.