My guess is she missed some basics and doesn't know how to catch up. A tutor can really help with this. If her school doesn't have a computer lab check the local community college. Remedial math instruction is a staple in most of them and the lab they have will most likely have a few different methods to help.

NovaNet* has a very good track record in this area. See if her school has it.


*Ob disclosure, NovaNet is one of the products my company offers.