The company paid $20,160 cash to settle the account payable created on April 3.

I have to correctly write a journal entry for the above -
(I wrote) 4/3 Account Payable for 20160 (under credit).
I am told this is incorrect what am I missing.
Should I be adding it to my cash as well?

The most important thing to grasp about accounting is it is a double entry system comprised of debit and credits in equal amount therefore the correct entry is debit account payable, that is; reducing the accounts payable balance, and credit cash; reducing the cash balance

If you were to add it to cash you would be doing the wrong thing and whatever you wrote regarding accounts payable is meaningless