what is n+n+3+2(n+3) simplified

n+n+3+2(n+3)

Well, you should always add like terms.

n+n=2n

Then you should use distributive property

2(n+3)

(2*n)+(2*3)

2n+6

2n+2n+3+6

Add like terms

2n+2n=4n, and 3+6=9

4n+9 is your answer.