Question 705798
x+y=1 MULTIPLY BY 2 & ADD. 
-2x+y=4
2X+2Y=2
--------------
3Y=6
Y=6/3
Y=2 ANS.
X+2=1 
X=1-2
X=-1 ANS.
PROOF:
-2*-1+2=4
2+2=4
4=4