Hello Everyone- Im stuck please help

Im using Collums A, B, C AND Cell D1
Collum A =Account
Collum B=Reference
Collum C=dollar amount

In cell D1 I would like the sum of Column C if rows with A with a value of
101, and B with a value of 201. Or is it better to have the sum of A and B
=302 within a row.
In this ledger their will be different accounts if that helps.

Well, thanks for your time and help,
-Markitos