Step-by-step explanation:
the slope of a line is the ratio "y coordinate change / x coordinate change" when going from one point to another.
I think I can recognize two good points with integer coordinates :
(-30, -90) and (70, 70)
x changes by +100 (from -30 to 70)
y changes by +160 (from -90 to 70)
the slope is then +160/+100 = 16/10 = 8/5
