What is the slope of a line containing 0-6 and 40?

Let (x1, y1) = (0, 6) and (x2, y2) = (4, 0), then

slope = m = (y2 - y1)/(x2 - x1)

m = (0 - 6)/(4 - 0) = -6/4 = -3/2

Thus, the slope of a line that passes though points (0, 6) and (4, 0) is -3/2.