An urgent joke is to buy fish, which probably means to buy a fish head 10 yuan, and to buy a fish as long as 5 yuan.

It is estimated that the man didn't buy all of them, but only a part. Answer 2: 10 yuan is the price per catty, and the prices of fish head 3 yuan, fish body 4 yuan and fish tail 3 yuan are also estimated to be the prices per catty, so those who sell fish will definitely lose money, and they will lose a lot. If the fish head weighs 1 kg, the fish body weighs 2 kg and the fish tail weighs 1 kg, according to the fish selling algorithm, the total * * * is (1+2+1) *10 = 40 yuan, and according to the fish buying algorithm, then .