a) Let p and p+2 be twin primes. Prove that sigma(P+2)=sigma(p) + 2

b)Prove or disprove the converse of part a above.

For Part a i just can seem to equate the 2.

I get that sigma(P+2) is [(P+2)^2 - 1]/[(P+2)-1] and rearranging i get

P^2 + 4p +4 / P+1

and then i get that sigma(P) +2 is [P^2-1/P-1] + 2 and rearranging i get

2p^2 +4p -6 / 2(P-1)

Maybe i am approaching it the wrong way?