at which point will the graphs of the
equations 2x+y=8 and x-y=4 intersect
We're looking for an x,y pair that satisfies
both equations. One equation has a positive
y term; the other has a negative y term.
Add the two equations to eliminate y.
2x + y = 8
+(x - y = 4)
-----------------
3x = 12
x = 4
Plug that value into one of the equations
to solve for y.
x - y = 4
4 - y = 4
-y = 0
You can multiply both sides by -1
-y * -1 = 0 * -1
y = 0
The x,y point we are looking for is (4, 0)