"Backs at you" is an informal phrase used as a response to someone who has wished you well or has greeted you in a friendly manner. It is often equated with the similar phrase, "same to you". However, there are other synonyms that can be used in place of "backs at you". These include "ditto", "likewise", "right back at you", "you too", and "same here". These synonyms reflect a shared sentiment of goodwill and positivity in return to someone who has expressed the same. It is important to note that these phrases are typically used in informal conversation, and may not be appropriate in more formal settings.