Stamps Office Supplies recently reported $15,500 of sales, $8,500 of operating costs other than depreciation, and $1,700 of depreciation. It had $10,000 of bonds outstanding that carry a 6.0% interest rate, and its federal-plus-state income tax rate was 35%. How much was the firm's earnings after taxes? a. $4,700 b. $4,870 c. $1,645 d. $3,055