(x+y)/2+(x-y)/6=1
x/2+x/6+y/2-y/6=1
2x/3+y/3=1
2x+y=3(1)
3(x+y)-4(x-y)=4
3x+3y-4x+4y=4
-x+7y=4(2)
(1)+2*(2)
y+14y=11
y=11/15
x=7y-4=17/15