Find the value of c such that the three points (5, 5), (-3, 7) , 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.
Slope = [ 7 -5 ] / [ -3 - 5 ] = 2 / -8 = -1/ 4
So
[ c - 7 ] / [ -6 - - 3 ] = -1/4
[c - 7 ] / [ -3 ] = -1/4
c - 7 = (-1/4) ( -3)
c - 7 = 3/4
c = 3/4 + 7 = 31 / 4
