Sorry if my explanation is hard to follow. I'm dumb.
I have a budget spreadsheet with two sheets. First sheet is titled "Summary" and the second "Transactions," where I log financial transactions. I want a cell (Q18) from my first sheet to return the sum of two other cells (P18-C42 from the "Transactions" sheet) if any cell from Column G on the transactions sheet shows "Amex."
The Transactions sheet consists of three columns (Date, Amount, and Credit Card...A,B, and C respectively). What I want is if I log a transaction, say a $100 payment on my Amex (A1=date, B1=$100, C1=Amex), then cell Q18 from the Summary page will calculate the sum of P18-B1 from the Transaction page.