Answer :

Parkourpeep
To find the slope the coordinates can be inputted into (x2 - x1)/(y2-y1)
(-8-1)/(9+9)
-9/18
-.5
y=-.5x+b
To find b input one of the coordinates into the equation
-9=-.5(1)+b
-9=-.5+b
-8.5=b
The final equation will be
y=-.5x-8.5