Step-by-step explanation:
the slope of the line is expressed as the ratio
y coordinate change / x coordinate change
when going from one point to the other.
the trick in such a situation is to find good points on the chart that are crossed by the line. and by "good" I mean points with round integer coordinates.
I see 2 such points :
(-3, 4) and (1, -3)
x changes by +4 (from -3 to 1)
y changes by -7 (from 4 to -3)
the slope is therefore -7/+4 = -7/4