What is the slope of the graph of the equation below?
x+y=5
a. 5
b. -5
c. -1
d. 1

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.