Marwicks Pianos, Incorporated, purchases pianos from a manufacturer for an average cost of $1,489 per unit and then sells them to retail customers for an average price of $3,400 each. The companys selling and administrative costs for a typical month are presented below:

CostsCost FormulaSelling: Advertising$970 per monthSales salaries and commissions$4,812 per month, plus 4% of salesDelivery of pianos to customers$60 per piano soldUtilities$669 per monthDepreciation of sales facilities$4,917 per monthAdministrative: Executive salaries$13,508 per monthInsurance$718 per monthClerical$2,524 per month, plus $37 per piano soldDepreciation of office equipment$895 per month

During August, Marwicks Pianos, Incorporated, sold and delivered 58 pianos.

Required:

1. Prepare a traditional format income statement for August.
2. Prepare a contribution format income statement for August. Show costs and revenues on both a total and a per-unit basis down through contribution margin.

Please explain how to do the sales salaries and commissions part for the contribution format.