From the data presented below, calculate the following ratios:

a.rate of return on total assets

b.rate of return on common stockholders' equity

c.gross margin Ratio/ rate of return on net sales

Net income	$ 70,000
Total assets, January 1, 2011	500,000
Total liabilities, December 31, 2011	175,000
Net sales	900,000
Interest expense	20,000
Current assets, December 31, 2011	150,000
Current liabilities, December 31, 2011	75,000
Income tax expense	25,000
Total assets, December 31, 2011	575,000
Stockholders' equity, January 1, 2011	300,000
Stockholders' equity, December 31, 2011	400,000
Common share outstanding for 2011	100,000