Learn Dutch: Werkt u in het restaurant? - Do you work in the restaurant?

The rule for dropping the -t in questions only applies to the informal word for you, jij (or je). For example, it would be werk je?. Because u is the formal you, it keeps the -t.

Why does the sentence start with the verb werkt instead of the subject u?

In Dutch, you make a yes/no question by swapping the order of the subject and the verb. Instead of saying U werkt (You work), you put the verb first: Werkt u?.

Where is the word "Do" in the Dutch sentence?

Dutch doesn't use "do" to make questions like English does. Instead of saying "Do you work?", Dutch simply flips the verb and subject to ask "Work you?" (Werkt u?).

Why is it het restaurant and not de restaurant?

In Dutch, every noun gets either de or het for the word "the". Restaurant is a neuter word, which means it always takes het. It is best to memorize the "the" word whenever you learn a new noun.