{x/2+y/3=2,0.2x+0.3y=2.8
x/2+y/3=2
3x+2y=12 (1)
0.2x+0.3y=2.8
2x+3y=28 (2)
由(1)*2-(2)*3得
6x+4y-6x-9y=12*2-28*3
-5y=-60
y=12
x=-4