1)x+y=-5
x+y+5=-5+5
x+y+5=0
2)x-y=3
x-y-3=3-3
x-y-3=0
3)x-5y=3
x-5y-3=3-3
x-5y-3=0
4)x=3y=0
(x,y)=(0=0)
0=3*0=0
0=0=0
(x,y)=(0,0)
5)2x+4y=6
2x+4y-6=0
x+2y-3=0
