When writing a formal letter, when you don't know the recipient's name, how would you address the person and close the letter?

Choose the appropriate option :-

Dear Sir/Dear Madam, Yours faithfully

The appropriate option for addressing the person and closing a formal letter when you don't know the recipient's name is:

Dear Sir/Dear Madam, Yours faithfully

This is a common and respectful way to address someone when you don't have a specific name, and "Yours faithfully" is a standard formal closing for such letters.