Firstly, you have to understand that if you talk about slope is a similar word gradient of the graph. So if you are calculating slope you have to use gradient formula:
m= Y2-Y1
X2-X1
therefore, in order for you getting first box & second box you have to use this formula above.
First box answer is:
Points fromthegraph (-2:-2) & (-3:-3)
m= Y2-Y1
X2-X1
m = -3-(-2)
-3-(-2)
m = 1
Second box answer is:
Points fromthegraph (3:3) & (4:4)
m= Y2-Y1
X2-X1
m= 4-3
4-3
m= 1
Third box answer is:
= 4
Forth box answer is:
= -3