Answer
$$13z^2 -2z+10$$
Work Step by Step
Like terms must (1) be raised to the same power and (2) consist of the same variable (i.e. x and y are not like terms). It is also important to note that numbers are all like terms with each other when not multiplied by anything. Thus, combining like terms, we obtain:
$$5z^2 +8z^2 -2z +10 \\ 13z^2 -2z+10$$
