Please help explain this so I can understand how to this on my own. Thank you

Using the data in the following table, , calculate the return for investing in Boeing stock (BA) from January 2, 2008, to January 2, 2009, and also from January 3,2011 , to January 3, 2012, assuming all dividends are reinvested in the stock immediately. Return from January 2, 2008, to January 2, 2009 is \%. (Round to two decimal places.) Return from January 3, 2011, to January 3, 2012 is \%. (Round to two decimal places.) Data table (Click on the following icon in order to copy its contents into a spreadsheet.)