bearing in mind that a solution to a system of equations is where their graph intersect or meets, Check the picture below.
$14.60 would be your answer
Three or more points are collinear, if slope of any two pairs of points is same. With three points A, B and C, three pairs of points can be formed, they are: AB, BC and AC. If Slope of AB = slope of BC = slope of AC, then A, B and C are collinear points