When you have two points you can find the slope with the next formula:
[tex]m=\frac{(y_2-y_1)}{(x_2-x_1)}[/tex]You have the points:
P1 (7, -1)
P2 ( -6 , -1)
[tex]m=\frac{(-1-(-1))}{(-6-7)}=\frac{(-1+1)}{(-6-7)}=\frac{0}{-13}=0[/tex]The slope of the line that passes by the points (7, -1) and (-6 ,-1) is 0