[tex] \Large{\boxed{\sf Comment \ vous \ appelez-vous?}} [/tex]
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When addressing your parent's coworker, who is likely an acquaintance or stranger to you, it's appropriate to use the formal form of the question. In French, that formal form is know as "le vouvoiement." It a formal way to address someone to show respect or politeness. It mostly consists of using the second-person plural conjugation of the verbs, which always ends with -ez.
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In general, we always use "le vouvoiement" when addressing people we do not know, except for children or teenagers.
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Therefore, the best option is:
Comment vous appelez-vous?
Translation: What's your name?
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Note: "Comment t'appelles-tu ?" also translates to "What's your name?", so the difference can only be noticed in French.
