Fully Factorising and Simplifying with negative indicies

I'm having some issues with Factorising when fractions are involved, and also with Simplifying to remove all negative indicies. I have an exam coming up and I'm trying to work through some lecture notes but can't seem to find much on what I need to know.

So to start with Factorising. Fully factorise the following: A) 6ab²c + 3da²c = 3ac(2b²+da)

So I'm pretty sure that's correct, and if so the rest I have done are likely correct. However what I'm struggling with is this (-3/4 and -9/2 are written as fractions)

B) - 3/4yx - 9/2x²y²

I honestly am unsure of how to even approach it, and I can't seem to even find resources on YouTube for specifically binomial Factorising with fractions on both sides. I would love a step by step on how to complete this, as I should be able to then complete the rest on my own.

Next up is something that is probably simple but I can't seem to grasp yet.

Simplify these expressions whilst removing all NEGATIVE indicies. ( '/' means it's a fraction)

A) X/y-¹ =

B) n-¹n2n-¹ =

C) (m-²)-²

There are a lot more but hopefully I can grasp what I need to do for these qoth some help.

Thanks for the help!