Answer:
Line 1: 
Line 2: 
Line 3: 
Line 4: 
Line 5: 
Line 6 : 
Line 7: 0
Line 8: 0
Line 9: 
Line 10: 
Line 11: 0
Line 12: 
Step-by-step explanation:
Slope of line is given by the formula:

Line 1:
The change in
coordinate is zero.
Therefore slope of line 1 is
.
Line 2:
Change in
coordinate = -4
Change in
coordinate = 3
Slope = 
Line 3:
Change in
coordinate = 4
Change in
coordinate = 3
Slope = 
Line 4:
The change in
coordinate is zero.
Therefore slope of line 4 is
.
Line 5:
Change in
coordinate = 7
Change in
coordinate = 3
Slope = 
Line 6:
Change in
coordinate = -7
Change in
coordinate = 3
Slope = 
Line 7:
Change in
coordinate = 0
Slope = 0
Line 8:
Change in
coordinate = 0
Slope = 0
Line 9:
The change in
coordinate is zero.
Therefore slope of line 9 is
.
Line 10:
The change in
coordinate is zero.
Therefore slope of line 10 is
.
Line 11:
The change in
coordinate is zero.
Therefore slope of line 11 is 0.
Line 12:
The change in
coordinate is zero.
Therefore slope of line 12 is
.