At our school we have a "summer packet" we have to complete. In this packet was the following problem:
At first the "sum" part puzzled me. I had no idea why they would quiz us on basic arithmetic in 6th grade. But then I realized, the exercise is not about just adding area and perimeter, it is (probably) about adding the units. Area+Perimeter is $inches+inches^2$ which I have no idea how to do. Wolfram alpha said they were incompatible units. We all know from area that $inches\times inches = inches^2$ but my question is, what unit is $inches+inches^2$?
Good for you, you found a mistake (or a trick on your teacher's part) in your summer homework. There are two ways to acknowledge the mistake and still answer.
You could write that there is no answer because you can't add different units.
Alternatively you could write the sum of the numbers and indicate that there are no units because you can't add inches and inches squared.