I think it is 31x.....
Just tell me if it is correct. So I can correct myself.
:) :) :)
Why you deleted my answer?

When adding polynomials :

Adding polynomials is just a matter of combining like terms, with some order of operationsconsiderations thrown in. As long as you're careful with the minus signs, and don't confuseaddition and multiplication, you should do fine.There are a couple formats for adding and subtracting, and they hearken back to earlier times, when you were adding and subtracting just plain old numbers. First, you learned addition "horizontally", like this:
6 + 3 = 9. You can add polynomials in the same way, grouping like terms and then simplifying.
Simplify (2x + 5y) + (3x – 2y)I'll clear the parentheses, group like terms, and then simplify:

(2x + 5y) + (3x – 2y) 
  =  2x + 5y + 3x – 2y
  =  2x + 3x + 5y – 2y
5x + 3y

So....The answer for your question:

=12x + 21