Answer:
(-6,-18) & (2,6) -----------> 3
(12,6) & (-4,-2) ----------->

(5,-19) & (6,-23) ----------> -4
(3,4) & (3,9) ---------------> unidentified
(1,-10) & (2,-15) -----------> -5
(-1,8) & (3,8) ---------------> 0
(0,0) & (21,14) ------------->

Explanation:
Use this formula to find all of these slopes.
