I need some math help please

I start with:
2(r+n)(r+n-1) + 3(r+n)-1

I end with:
(2n+2r-1)(n+r+1)

Can you please show me the intermediate steps

Let r+n = t

so, ur eqn becomes :
2t(t-1) + 3t - 1

2t^2 - 2t + 3t - 1

2t^2 + t - 1

2t^2 + 2t - t -1

2t(t+1)-1(t+1)

(2t-1)(t+1)
now t=r+n
so, answer is (2n+2r-1)(n+r+1)

Start with:

2(r+n)(r+n-1) + 3(r+n)-1

Multiply by 2:

(2r+2n)(r+n-1) + 3(r+n) - 1

Multiply ()()

2r² + 2rn -2r +2rn +2n² -2n + 3(r+n) - 1

Multiply by 3:

2r² + 2rn -2r +2rn + 2n² + 3r +3n - 1

Group like terms:

2r² +2rn+2rn -2r+3r +2n² +3n - 1

Combine like terms:

2r² + 4rn + r + 2n² +3n - 1