Like terms must have the same variables and those variables must have the same powers.
[tex]7a^2b^3[/tex] and [tex]9a^2b^3[/tex] are like terms, because they both have [tex]a^2[/tex] and they both have [tex]b^3[/tex].
[tex]7a^2b^3[/tex] and [tex]7a^3b^2[/tex] are NOT like terms, because the powers no longer match.
In your example, do you have the same variables and do the variables have the same powers in both expressions?