Formal:
* Où est...? (Formal, general)
* Où se trouve...? (Formal, more specific)
Informal:
* Où est-ce que...? (Informal, general)
* Où est...? (Informal, if you're close to the person)
Examples:
* Où est le musée? (Where is the museum?)
* Où se trouve la gare? (Where is the train station?)
* Où est-ce que je peux trouver une boulangerie? (Where can I find a bakery?)
* Où est ton téléphone? (Where is your phone?)
Note:
* Où means "where" and is always used in these phrases.
* Est is the verb "to be" in the present tense, and it changes depending on the subject (e.g., "est" for singular nouns, "sont" for plural nouns).
* Se trouve means "is located" and is often used for places or things that are fixed in a particular location.
* Est-ce que is a way to make questions more polite, but it is not always necessary in informal situations.
Choose the appropriate phrase based on the formality of the situation and who you are talking to.