x+y+z=30 (1)3x+y-z=50 (2)5x+4y+2z=m (3)(1)+(2)4x+2y=802x+y=40 (4)(2)*2+(3)6x+2y+5x+4y=100+m11x+6y=100+m (5)(4)*6-(5)12x+6y-11x-6y=240-100-mx=140-my=40-2x=2m-240z=30-x-y=130-m因为x,y,z均为非负数所以x>=...