Step-by-step explanation:
equation of the line passing through two points
x-x1/x2-x1=y-y1/y2-y1
x-(-8)/1-(-8)=y-2/9-2
x+8/9=y-2/7
7x+56=9y-18
9y=7x+56+18
y=7/9x+74/9
y=mx+b m is the slope
so m=7/9
there is a short way showing slope shown in the picture
