Combining like terms means adding or subtracting the coefficients of terms that have the same variables. x^2 can only be combined with x^2, x^4 with x^4, and so on.
In your problem, you have two terms that have an x^5 and two terms that have no variable, so you would combine the two x^5 terms and then you would combine the two non x terms.
An example: 7x^2 + 3 - 4x^2 + 5x + 2
7x^2 and -4x^2 are like terms.
3 and 2 are like terms.
5x has no like terms so it just stays the same.
7x^2 - 4x^2 = 3x^2 and 3 + 2 = 5 and 5x = 5x
So the answer would be 3x^2 + 5x + 5