(2) Party A alone: it takes 60 days, and the * * fee is: 60×80+60×5 = 5 100 yuan.

Single B: It takes 40 days, and the cost of * * is: 40×120+40× 5 = 5,000 yuan.

Cooperation between Party A and Party B: It takes 24 days to produce 16+24=40 pieces every day, and the cost of * * * is: 24× 80+24×120+24× 5 = 4,920 yuan.

Therefore, the cooperation between Party A and Party B saves money and time.