Be surprised how little maths you actually need to pass the ATPL's.
Important ones
speed, distance, time
re-arrange formulas, ie f=m x a, also m = f/a, also a = f/m
pt = ps + pd, therefore pd = pt - ps, therefore ps = pt - pd
Once you learn the theory of re-arranging formulas, it can be applied to any other formula
Trig really helps a lot, just basis stuff, like sin cos tan, triangles, circumfrance, radius, diameter, pie
Once you get the basic understanding, you can apply that to all the equations you will come across while doing all your theory
Dont get too worried about it, just make sure you are happy with the basics