设甲单独x天1/x+1/(x-60)=1/40两边乘40x(x-60)40(x-60)+40x=x(x-60)40x-2400+40x=x²-60xx²-140x+2400=0(x-20)(x-120)=0x1=20x2=120甲单独 120天乙单独 120-60=60天请好评~在右上角点击【评价】,然后就...