Mathematics is not difficult. Your child should have confidence, 80% is the basic score. Personally, I suggest to find out what to take in the college entrance examination first. The outline has been clearly defined. If you don't understand, you can do the questions in the textbook first, do them in moderation, and focus on understanding. Take a notebook and record the wrong questions on the math paper, classify them, read more, and you won't know if you are wrong. Practice repeatedly to strengthen your relationship with the math teacher.
For big questions like series, trigonometric functions and geometry, the first question is relatively simple. Be sure to get the score of the first question and practice more. Don't urge the child to put pressure on her, encourage her more, talk to her and help the child through the sadness.