Gildan Activewear Inc. reported net sales (in U.S. millions) of $1,311 in 2010 and $1,038 in 2009. The company also reported a profit of $198 in 2010 and $95 in 2009. Assets at the end of 2010 were $1,321; at the end of 2009, $1,074; and at the end of 2008, $1,095.

(a) Calculate Gildan's asset turnover, profit margin, and return on assets for 2011 and 2010.

(b) Comment on whether the return on assets changed primarily due to a changing asset turnover or a changing profit margin.