Homework help?

Income Statement as follows: Sales $31,300 Cost of goods sold - 16,800 Gross profit - $14,500 Selling & Admin. exp. - $16,700 Income from operations - $(2,200) I cannot understand how to get Variable cost of goods sold and Variable selling and administrative expenses I did get Fixed Costs 15% of Cost of Goods Sold = $2520 and 40% of Selling and Admin Exp = $6680