You can put this solution on YOUR website! x+y=4 or y=-x=4 (red line)
x-2y=1 or -2y=-x+1 or y=-x/-2+1/-2 or y=x/2-1/2 (green line) (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions -x +4 and x/2 -1/2).
Ans. (3,1)
Proofs:
3+=4
3-2*1=1
3-2=1