Canyon Tours showed the following components of working capital last year: Beginning End of Year Accounts receivable $ 26,400 $ 24,200 Inventory 13,200 14,900 Accounts payable 15,700 18,900 a. What was the change in net working capital during the year? (A negative amount should be indicated by a minus sign.) b. If sales were $37,200 and costs were $25,200, what was cash flow for the year? Ignore taxes.