I think math is something that requires a lot of practice for some people. I know in grade school we got TONS of homework, basically I think they acted like mental "pumping iron" for the math part of the brain. For higher math, I found that if I could link it to a real world example (these abound in physics, lol) I had much better luck with it.

But I think you need some unhurried, one-on-one time to find whatever mental "trick" might work.