@jividemin
In numerical terms or in conceptual terms?
Your example frankly is just not the way an income statement, even a simple one, is calculated. The numerical answer is as Trustinglife so ably shows us, is $ 28,200.
In the real world you would not have your gross profit amount without first calculating cost of goods sold. It should go Sales less cost of goods sold =gross profit and not the way it is shown in your example. Cost of goods sold is simply the accounting value or historical cost of the items you sell, most likely, at a profit. Cost can be simple, as what you paid for an item for resale plus freight and/or cost of importation or complex like a machine with 16,000 parts.
Similarly, you determine your operating expenses like payroll, payroll taxes, fringe benefits, commissions, 401k, rent, telephone, IT repairs, legal, travel, etc, etc.
When that amount is calculated by summing the relevant accounts from the general ledger or subsidiary ledgers, you have operating expenses. Operating expenses are deducted from gross profit to determine pre-tax income, not net income as in your example..
This seems to be an odd way to teach accounting. Where do you attend school?
SRM