The formula I use is not giving me the right answer.Can someone please help. I used cost of good sold percent=cost of goods/net sales. My book does not give any other formulas for figuring the percentages. Here is the problem. The blank spots are the percents I need.

At the end of 2012 the following information is available for Chicago and St. Louis companies.
Chicago St.Louis
Sales 3,000,000 3,000
Cost of Goods Sold 1,800,000 2,100
Selling and Admin Expenses 960,000 780
Total Assets 3,750,000 3,750
Stockholders Equity 1,000,000 1,200

Prepare common Income statements for each company:
Chicago % St.Louis %
Sales 3,000,000 100 3,000 100
Cost of Goods Sold -1,800,000 -2,100
Gross Margin 1,200,000 900
Opperating Expense -960,000 -780
Net Income 240,000 8 120 4