Which would be the "Cost of Goods"?

Hello, I'm trying to find the Gross profit rate and profit margin but I can not figure out which of these to use as the cost of goods which I need to find the profit rate...

101 Cash 17,800

112 Accounts Receivable 14,400

126 Supplies 2,300

130 Prepaid Insurance 4,400

151 Equipment 46,000

152 Accumulated Depreciation-Equip 18,000

200 Notes Payable 20,000 (Note: $5,000 of the notes payable become due in 2015.)

201 Accounts Payable 8,000

212 Salaries and Wages Payable 2,600

230 Interest Payable 1,000

311 Common Stock 15,000

320 Retained Earnings 9,800

332 Dividends 12,000

400 Service Revenue 86,200

610 Advertising Expense 10,000

631 Supplies Expense 3,700

711 Depreciation Expense 6,000

722 Insurance Expense 4,000

726 Salaries and Wages Expense 39,000

905 Interest Expense 1,000

Totals 160,600 160,600

(I don't need the rate and margin/i don't need you to do my homework for me,I Just can't figure out which of these entries I would use to find it)