Find the value of c such that the three points (5,5), (-3,1) and (6,c) lie on the same line. Note: Three points are on the same line if the slope of the line through any two points is always the same.
First, let's find the equation of the line through (5, 5) and (-3, 1).
slope = (1 - 5) / (-3 - 5) = -4 / -8 = ½
equation: y - 5 = ½(x - 5) ---> y = ½x + 2½
For the point (6, c) ---> c = ½(6) + 2½ ---> c = 3 + 2½ ---> c = 5½
+231 
