Lengthening the credit period Parker Tool is considering lengthening its credit period from 30 to 60 days. All customers will continue to pay on the net date. The firm currently bills $420,000 for sales and has $300,000 in variable costs. The change in credit terms is expected to increase sales to $510,000. Bad-debt expenses will increase from 1% to 1.5% of sales. The firm has a required rate of refum on equal-risk investments of 20%. (Note: Assume a 365-day year.) a. What addibional profit contribution from sales will be realzed from the proposed change? b. What is the cost of the marginal investment in accounts rocoivable? c. What is the cost of the marginal bad debts? d. Do you recommend this change in credit terms? a. The additional profit contribution from an increase in sales is $ (Round to the nearest dollar.)