If 3 points are collinear the solve for t (-3,3) (t,-1) (8,6)
Let A(-3,3), B(t,-1), C(8,6) be the three points.
If they are collinear, the slope of line AB would be the same as the slope of line BC.
The slope m of a line between two points is given by
m = (y2-y1)/(x2-x1)
Equate mAB and mBC in terms of t.
Solve for t.