You should consider posting these types of questions on the DAT board.
Without more context into your situation, it is difficult to be more specific that this: you improve on these sections by practicing...by practicing methodically, intensely, and with a game plan. There is no magic answer here and definitely no shortcut. But if practice is not helping, then you're likely lacking a foundation for these subjects. Then I'd recommend you put your pride away and start at the beginning with the basics...like multiplication tables, multiplying/adding/simplifying fractions, distribution, etc. In reading, if you're having trouble, slow down and try to understand how arguments are made and understand keywords and structure. Go slow and shoot for understanding. Once you feel comfortable, then speed up. High test scorers do these things naturally and implicitly. You'll just have to work hard to get to that point.