How to simplify variables and coefficients?

In simplifying variables and coefficients, you just have to add or subtract the coefficients with the same terms. The terms are the same when they both have the variable x and exponent.
Example 1:
      
You can simply add 5 and 6 and copy variable x^2 because they are similar terms.
But for expression , coefficients 4 and 6 cannot be added because they are not the same terms.

Example 2:
Simplify
  

Iagree that is the answer to the question