Kenji, I'll toss in a couple of cents worth. Math is like reading. However, it's a little different for many people. Many people are at an early reading level with Math. They can read the words. Sometimes they can read and comprehend whole sentences. Many have problems following a whole paragraph for math.
My suggestion for people who have traditionally be poor at math, and want to us PR to improve is to go back. Go back to a level of math that you feel magnificiently confident with and PR and try those mind probing problems at the end of the chapter.
This may mean going back quite a few years. If you stay with a level until you feel really good with it, then you will build your ability for comprehending Math.
I've helped a few people with Math and I've noticed that if I try to help them with what they are working on it doesn't really sink it. However, if I talk to them and try and understand their level of understand. Then if I rephrase the problem and start from where they have a good comprehension, then they learn the material. It seems longer than just explaining all the details, but in the long run it isn't. They need a starting point to build from. Some place to hang the new knowledge as the acquire it.
Another note: Math books are written for people who are good a reading Math. I've read some old Math texts and they were written a lot differently. There was a lot more explaining of problems and concepts. Newer texts are more mathematically rigorous and detailed, but the are only so - so as instruments for educating. Not much good if only 20% of the class can teach themselves from the text alone.
Okay, that was probably 3 cents worth. Good luck,
Iam2