from reading the graph, there are different ways to solve it. Fist find two "pretty points" that intersect on a line.
like (2,2) and (6,1)
Then find the difference
(2,2) for 2 to get to 6 is -4
(6,1) for 2 to get to 1 is -1
then change of y over the change of x : 1 over -4 which is 1/-4
so the slope is 1/-4
Second one:
(4,-3) 4 get to 5, 1
(5,1) -3 get to 1, 4
change of y over change of x : 1 over 4, 1/4
m= 1/4