You don't have to be a mathematician, or even "good" at #maths, to help your #children learn maths. You just have to model resilience and positivity towards what they're doing, and to avoid reinforcing negative tropes.
A #thread:
Do they seem to have been taught a different method for something you remember? Not a problem: get them to #teach you theirs, and encourage them to try to understand yours. See if you can spot similarities. Why do both work? Can you find reasons why one may be "better" than the other (there are no right answers here, but just being more familiar doesn't count)?
Are they doing something you don't recognise, or maybe you do recognise but never got the hang of it? Get them to #teach you as much of it as they can. Work together on it. Admit that you don't understand it YET but don't use this as an excuse to not engage. Learning new things is a positive thing. Not understanding something is a prerequisite for learning something new.
Model mathematical #positivity at times - not just when they're doing homework! Ask #mathematical questions about everything (look for patterns in things & try to explain them, essentially).