Question

In the sentence You may have an apple or an orange but you can't have both . Where would the commas be ?

Answer 1

Between the or and apple and also the orange and but

Answer 2

The comma would end up between but and orange.

"You may have an apple or an orange, but you can't have both."

This is because you're coming to a conjunction, which usually has a comma preceding, or coming before, it.