May June July Sales (units) 700 800 800 Selling price $5 Expenses $4,000 $4,500 $5,000 Opening cash Balance $5,000 Cash from sales is collected one month in arrears At the start of may $2,000 was owed by customers from the previous month The expenses include depreciation of $800 a month Expenses are paid during the month they are incurred a) From the data above, calculate the closing cash balance for the months of May, June and July, please show all your workings (4 points) b) List two advantages of a cash budget (2 points)