I need help with figuring out the formula to get the 'Cash Balance, Beginning' for March - June, where are these numbers coming from, what are the calculations for it??

Heron, Inc. Cash Budget For the 6 mos ending June '10 01 12 Jan '10 Feb '10 Mar '10 Apr '10 May $10 June '10 $ mos total 03 Cash balance, beginning 15,000 $ 15,000 15.344 1 $ 15,529 $ 15,887 $ 15,571 $ 92,331 M4 Add collections from customers 104.200 106, 132 112,300 134.328 171,315 214.572 S 842.847 15 Total cash available 119,200 121, 132 127.644 149,857 187,202 230, 143 935, 178 16 Less disbursements: Cash disbursements for merchandise purch 43,200 43,968 50.515 61.690 76,306 87.847 $ 363,526 Cash disbursements for operating expenses 50,000 51.820 52,600 57.280 63,325 69. 175 344.200 Equipment purchases 50,000 30,000 80,000 Dividends 12,000 12,000 Total cash disbursements 143.200 125,788 115,115 118,970 139.631 157,022 799.726 2 Excess of receipts over disbursements (24,000] (4,656) 12.529 30.887 47.571 73, 121 135,452 Financing: Borrowing-note 39,000 20,000 3,000 62,000 15 Repayments-note (15,000) (32,000) (15,000) (62,000) Total financing 39,000 20,000 3,000 (15,000) (32,000) (15,000) 17 Cash balance, ending 15,000 $ 15.344 $ 15,529 $ 15,887 $ 15,571 $ 58, 121 $ 135,452 18