To determine the slope of the line, identify two points that lie on it. Let x be zero and solving for y gives y = 5. Hence, the point (0, 5) lies on the line. Furthermore, by letting y be zero and solving for x gives x = 5. Thus, the point (5, 0) is also on the line. Use the formula for slope which is,
m = (y2 - y1) / (x2 - x1)
m = (0 - 5) / (5 - 0) = -1
Therefore, the slope of the line is -1.