could you please explain how to get the percentages please?

thank you so much!

Express the following comparative income statements in common-size percents. Using the common-size percentages, which item is most responsible for the decline in net income? Income Reason for Statement Decline in Net Income Express the following comparative Income statements in common-size percents. (Round your percentage ans decimal place.) GOMEZ CORPORATION Comparative Income Statements For Years Ended December 31 Current Year Prior Year % Sales 795,000 100.0 $635,000 100.0 Cost of goods sold 570,800 71.8 291,000 45.8 Gross profit + 224,200 344,000 Operating expenses 128,000 225,200 Net income $ 96,200 $ 118,800 $ Income Reason for Decline in Net Income >