x+y=2t z+x=3t y+z=4t ∴2x+2y+2z=9t x+y+z=9t/2
9t/2=27 => t=6
x+y=12 z+x=18 =>z-y=6
又：z+y=24
∴ z=15 y=9 => x=3
∴ x=3 ,y=9 ,z=15.