Following Is the Income Statement for Masters Corporation for the Year

Following is the income statement for Masters Corporation for the year ended December 31,2017:
Masters Corporation
Income Statement
For the Year Ended December 31, 2017 $\begin{array}{lc}\text { Net sales }&\$770,000\\\text { Expenses: }\\\text { Cost of goods sold } & 478,500 \\\text { Selling expenses } & 35,000 \\\text { General expenses } & 39,300 \\\text { Interest expense } & 42,000 \\\text { Income tax expense } & 35,000\\\text { Total expenses } &{629,800} \\\text { Net Income }&{\$ 140,200}\end{array}$ a_Calculate the gross profit percentage
b_Calculate the profit margin.