5x+4y-3x-2y+xy =(5-3)x+(4-2)y+xy=2x+2y+xy=2(x+y)+xy代入=2*5+2=14
5x+4y-3x-2y+xy=2x+2y+xy=2(x+y)+xy=2×5+2=12
=2x+2y+xy=2*5+2=12
X=5-Y5(5-Y)+4y-3(5-y)-2y+2=25-5y+4y-15+3y-2y+2=10+2=12