You don't understand, but after putting it in and taking it out a few times, the second basket weighs 40 Jin. Read the topic carefully. After several times, the weights of the three baskets are equal, that is to say, each basket is 120÷3=40 kg, the second box is put 15 kg first, and after taking out 8 kg, it is 40 kg, so it was originally 40+8- 15=33 kg.