The first time a customer bought several small commodities in a store, he spent 4 yuan. When he went to the store for the second time, he found that the price of each dozen (12 pieces) was reduced by 0.8 yuan. If he bought more than a dozen, he could buy them separately. In this way, the quantity of the same small commodities that he spent 4 yuan on the second time was 1.5 times that of the first time?

The first time a customer bought several small commodities in a store, he spent 4 yuan. When he went to the store for the second time, he found that the price of each dozen (12 pieces) was reduced by 0.8 yuan. If he bought more than a dozen, he could buy them separately. In this way, the quantity of the same small commodities that he spent 4 yuan on the second time was 1.5 times that of the first time?

Suppose that the first time he bought a small commodity is x pieces. 4x-41.5x = 0.812, the solution is: x = 20, which is the solution of the original equation. A: the first time he bought a small commodity is 20 pieces

How to improve the ability of comprehension and calculation?

In fact, the calculation ability is trained. You can find a few slightly difficult ones for him to do. If they are all right, they will pass the test. If they are wrong, they will be punished. In this way, she will practice more, and in order to avoid being punished, she will certainly do it carefully and check~~~~~~~~
Secondly, the problem of application problem is a problem of principle. You can find some guidance books to teach her to do it according to the examples. Explain the practice of the examples clearly, let her understand and then contact with similar problems. Don't do the problems at the beginning, so the effect is not good