原价x,降20%后是0.8x,要增加25%,1.25*0.8x = x
（1）人均定额是x,甲组总量 4x+20,乙组总量 6x - 20,(4x+20)/4 = (6x-20) /5,24x - 80 = 20x + 100,x = 180/4 = 45
(2) （4x+20)/4 = (6x-20)/5 + 2,x + 5 = 6x/5 - 4 + 2,x = 35
(3) x+5 = 6x/5 - 4 -2,x = 55
原价x,降20%后是0.8x,要增加25%,1.25*0.8x = x
（1）人均定额是x,甲组总量 4x+20,乙组总量 6x - 20,(4x+20)/4 = (6x-20) /5,24x - 80 = 20x + 100,x = 180/4 = 45
(2) （4x+20)/4 = (6x-20)/5 + 2,x + 5 = 6x/5 - 4 + 2,x = 35
(3) x+5 = 6x/5 - 4 -2,x = 55