2(x+y)-(x-y)=3………………①
(x+y)-2(x-y)=1………………②
①+②得:3(x+y)-3(x-y)=4
3x+3y-3x+3y=4
6y=4
y=2/3
①-②得:x+y+x-y=2
2x=2
x=1
∴原方程组的解是:x=1
y=2/3
2(x+y)-(x-y)=3………………①
(x+y)-2(x-y)=1………………②
①+②得:3(x+y)-3(x-y)=4
3x+3y-3x+3y=4
6y=4
y=2/3
①-②得:x+y+x-y=2
2x=2
x=1
∴原方程组的解是:x=1
y=2/3