Yes it is. Ax+By=C is standard form. :)
Given:
A line contains the points R(-1, 8), S(1, 4) and T(6, y).
To find:
The value of y.
Solution:
Three points are collinear if:

A line contains the points R(-1, 8), S(1, 4) and T(6, y). It means, these points are collinear.



Subtract 12 from both sides.

Divide both sides by 2.


Therefore, the value of y is -6.
The answers is the last one
Four million two hundred fifty thousand