Well if you use the subtraction method for elimination you get 2x+-2y=12 Now you can times one at a time by zero and find what each equals. 2(0) +-2y=12 y=-6 2x+-2(0)=12 x=6
In terms of points, a point that is coplanar is one that lies anywhere on the given plane while a point that is collinear is a point that lies anywhere on the given line.