Calculate operating income and net income Selling, general, and administrative expenses were $66,000; net sales were $300,000; interest expense was 7,100; research and development expenses were $31500; net cash provided by operating activities was $79200; net income was $16800; income tax expense was $7600; cost of goods sold was $165,000. Required: a. Calculate operating income for the period. b. Calculate net income for the period.