由已知,x + 6.6 + y = 20 + x + 5.6 + z = 20 + y + 9.8 + z = 20 ；化简可得：x + y = 13.4 ①；x + z = -5.6 ②；y + z = -9.8 ③；把①+②+③,可得2x + 2y + 2z = -2,所以x + y + z = -1,分别减去①,②,③可得：z = -14.4,y = 4.6,x = 8.8 ；综上所述,原不等式组的解为：{ x = 8.8{ y = 4.6{ z = -14.4