I'm a math teacher. You might consider getting her a private tutor. They can be expensive, but there are some good ones that are cheap. I suggest looking on thumbtack for one.

If you can't afford a tutor, there are tons of YouTube videos that explain math problems. Figure out what the math is called, google it, and find videos on it with her. Watch the videos with her. Learn along aside with her. Explain that you are willing to learn right now with her. It could be a good bonding experience, of learning math together with her. Hundreds of people make videos exactly around the concepts she is learning in school.

It could also work to email her math teacher and explain you want to help her but don't know math, and ask for recommendations of math videos on YouTube. Her teacher may have ones she would recommend that align with her class.