why does the increase of cash(from 7 to 15) result in a use of cash and not a source ?

The consolidated balance sheets for the Landon Lumber Company at the beginning and end of 2009 follow. The company bought $50 million worth of fixed assets. The charge for depreciation in 2009 was $10 million. Net income was $33 million, and the company paid out $5 million in dividends. - is this just to confuse ne? a. Fill in the amount of the source or use in the appropriate column. LANDON LUMBER COMPANY: BALANCE SHEET AT BEGINNING AND END OF 2009 (Millions of Dollars) Why is this a use of - Cash if it is going CHANGE Jan. 1 Dec. 31 Source Use Cash $ 7 $ 15e Marketable Securities 11 Net Receivables 30 Inventories Total current assets $ 90 $ 123