The slope of the line can be determined using the formula: (y2 - y1) / (x2 - x1).
Taking the first two points (0, 0) and (2, -2):
(0 - (-2)) / (2 - 0) = 2 / 2 = 1
Taking the second two points (2, -2) and (4, -4):
(-2 - (-4)) / (2 - 4) = -2 / -2 = 1
Since the slope is consistent between all pairs of points, the slope of the line is 1.