先解
2x-3y=3 (1)
3x+2y=11 (2)
(1)*2+(2)*3
4x+9x=6+33
x=3,y=1
代入另两个
3a+b=-1 (3)
6a+3b=3
2a+b=2 (4)
(3)-(4)
a=-3,b=8