Computing Gross Profit and Operating Income Following is an excerpt from the Packer Inc. year-end trial balance dated December 31, 2020. Selected Adjusted Trial Balance Amounts Acct. No. Description Debit Credit 400 Sales revenue $112,000 402 Consulting revenue 1,600 404 Gain on sale of investments 4,480 510 Cost of goods sold $40,000 511 Selling expense 17,600 512 Salaries expense 4,800 520 Rent expense 3,200 526 Insurance expense 800 528 Depreciation expense 1,600 530 Research and development expense 00 535 Loss on sale of investments 2,880 540 800 Interest expense Income tax expense 542 3,120 Required Hint: Consider consulting revenue nonoperating revenue. $ a. Compute gross profit for 2020. b. Compute operating income for 2020. $