POA is not very related to Maths actually; to do POA you only need
the basics ( addition, subtraction, multiplication and
division).
You still can pick up A-Maths in Poly (its a must for entry to
JC) and that to enrol into NUS you must have A-Maths so its
basically when you study and not a type of choice in the end ...
...
For my RP, A Maths = Advanced Maths. I only took it on year 2
sem 1 as my elective module, taking it helps to enrol into
univeristies in Singapore, but only if you pass this module get at
least a C for overall grade (UT + daily presentation).
Anyway, there are two parts of Advanced Maths. So, for what I
had taken was: A Maths Part 2 which is about linear equation (basic
algebra etc...)
And I would be deciding to take A Maths Part 1 during Year 3 sem
2.
Thus, there won't be problem to understand and pass it if
you do most contributions with the teammates in every of the
lessons for both A Maths modules and score well for the UTs
too.