This is a great question. Someone with a more academic background will hopefully answer your question with information about the links between math and music. There are lots of studies that show that teaching kids music can really help them improve in math. I've read articles about that in the past but am definitely now qualified to quote that research.
What I can say though (as a mom) is that music can be a wonderful opportunity for kids who are struggling academically to feel "good at something". Too often kids who get bad grades end up labeling themselves as "not smart". More often than not those kids are plenty smart, they just haven't been taught in a way that works for them or they haven't been supported at home in their academic efforts. If those kids try music and find that they are good at it, it can give them a huge confidence boost. Once they see that they can learn music, they start to believe that they might be able to learn other things (like math and reading). They stop feeling "stupid".
I've seem music give a real boost to so called "slow learners".