+569 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.
(c - 1)/(6 - 3) = (c - 5)/(6 - 5)
==> (c - 10)/3 = (c - 5)/1
==> c - 10 = 3(c - 5)
==> c - 10 = 3c - 15
==> 2c = 5
==> c = 5/2
