Maths queston. Help please! How do you make a the subject in P=n^2+a/n+a? (I must show working?

Hey, I don't know whether it's still helpful, but I can help with this. Sorry, I've only just seen this.
1) You times both sides by (n+a), which gives you P(n+a)=n^2+a
Then you can expand the brackets, giving you Pn+Pa=n^2+a

2) You take n^2 away from both sides which then gives you Pn+Pa-n^2=a
However, as there is a on both sides, you have to carry on

3) You take Pa away from both sides, giving Pn-n^2=a-Pa
You then need to take a common factor of a from the right hand side, giving you Pn-n^2=a(1-P)

4) You can then divide both sides by (1-P), which gives you a=(Pn-n^2)/(1-P)

Hope that helps!