In 2018, Modder Corporation reported net sales of $250,000, cost of goods sold of $137,500, operating expenses of $50,000, and income tax expense of $20,000. In 2017, it reported net sales of $200,000, cost of goods sold of $114,000, operating expenses of $40,000, other revenues of $10,000, and income tax expense of $15,000. (a) Calculate the gross profit and net income for each year. (b) Calculate the gross profit margin and profit margin for 2018.