如何在两个不同的表中使用SUM和INNER JOIN

I am stuck on a query where i have to show list of manufacturers and the Amount of Loan they took and Amount of Refund they returned. i have generated the query but i want to sum total no: of refunds of a manufacturer and total no: of Loans manufacturer has taken. and the difference , that is LoanTaken - RefundAmount = Remaining Amount. If its possible in the query.I am stuck on a query where i have to show list