They are unlike terms and cannot be added.
This is the answer.
There are often errors in the wording of a question, in particular, 'Solve' is often used instead of 'simplify'.
'Solve' should be used for an equation.
'Simplify' is used for an expression.
I took the liberty of changing the question from 'solve' to 'simplify'.
This type of question is often given when students are first learning algebra, to emphasis the following:
- only LIKE terms can be added.
- in algebra, an answer can have more than one term.
Students are often tempted to offer a single term as an answer in algebra, because in their experience, that had always happened.
They are not like terms, so they cannot be added.
There is no simplifying to be done.
This is the final answer.