When you say MATHS, it is not A level maths, but there are certain critical elements that you need, which a bright young person aged 13 would be capable of tackling.
1. Basic SUMS : + : - : x : % to name but a few. You get the drift
2. Basic equations
3. SIN COS TAN
Airline flying is very much NUMBERS orientated. You must feel totally comfortable as it forms part of the fundamental ingredients to the whole shooting match.
Start studying GEN NAV as your first subject. Get you into the mood.Fewest fact to learn. IT IS CRITICAL THAT YOU UNDERSTAND it, the LOGIC behind it. Don't attempt to learn it like a history book. That does not work.
Probably your THREE times table and being able to ADD 10 is the most important day to day calculation you MUST be capable of doing with your eyes closed, standing on your head, so to speak ~ TOD point
The above is the underarm test to start to check whether your brain is wired up correctly for aviation. Not all people make the grade; their talents lie elsewhere.