The formula for calculating the equation of a line is expressed as
slope = (y2 - y1)/(x2 - x1)
where
y2 and y1 are the y coordinates of selected final and initial points on the line.
x2 and x1 are the x coordinates of the selected final and initial points on the line.
From the graph,
when x1 = - 4, y1 = 2
when x2 = 4, y2 = 0
By substituting these values into the formula, we have
slope = (0 - 2)/(4 - - 4) = - 2/(4 + 4) = - 2/8
slope = - 1/4