letters : mail :: _______ : money

checks?

CHANGE

To figure out the analogy for the given relationship, we need to identify the connection between "letters" and "mail." In this case, "letters" are a type of correspondence that is sent through the medium of "mail," which refers to the postal system used for sending letters and packages.

Applying this understanding to find the analogy for "money," we need to identify a word that represents a system or method through which money is transmitted or exchanged. The word that fulfills this criteria is "currency."

Therefore, the answer is: currency : money.

Just as letters are sent through the medium of mail, money is exchanged using currency.