In the Cartesian coordinate plane, find the value of that makes the points , , and collinear.
If , , and are collinear, then the slope of is the same as the slope of .
We know that the slope, , of a line passing through 2 points and is given by
Using the coordinates of and , find the slope of .
The slope of is the same as the slope of , so we can say
Solve for .