1, the foundation is not enough, and it will be supplemented by accumulation. First of all, your basic knowledge may not be enough, including what you have learned so far and what you have learned in junior high school. For example, a topic may involve algebraic processing, using square difference formula or complete square formula, adding, subtracting, multiplying and dividing fractions in calculation, solving equations, etc. Therefore, there are many requirements for the topic, and any loophole in any knowledge point may lead to failure to answer. So the foundation needs a certain amount of time to accumulate.
2. Strengthen the understanding and application of knowledge. For a knowledge point, different people have different understandings of it when learning, and the depth of understanding may vary with the learning time. If you stay on the surface, you may not be able to do the problem, just like you are now, you can do this problem and you can't do the other one. This is a question of understanding and application. How to improve your understanding is, of course, thinking and brushing questions. When you brush the questions, you won't be prompted to look at the answers directly, see where your problems appear, fix them slowly and accumulate for a period of time. I believe this situation will get better.
3, clear goals, struggle. Learning is not a simple matter. It is impossible to improve quickly in a few days and months, but it takes a long time to persist. Some students feel that learning is very hard, and they can't persist after a period of time. What you need most at this time is to be clear about your goals and think about why you want to study, so that you can continue to stick to it.
This requires perseverance. Mathematics also needs to accumulate knowledge points, especially in junior high school, unlike primary school, which needs to accumulate a lot of theorems and formulas. We need to accumulate knowledge points by taking notes, and if we stick to it, mathematics will certainly get better.