Please show each working properly with an explanation for each step so that I understand

11. Selected Financial Information is shown for Waste Removal Systems Company "WSR for 2015 and 2016. 2015 2016 Revenue $600 $720 Operating Income 180 223 Earnings After Tax 65 56 291 Total Assets Shareholders Equity 245 160 189 = a. Calculate the Operating Margin % and Net Margin% for both years for WSR. FOR 2015 Operating 180 Operating Margin = = 30.0% Revenue 600 Net Income 65 Net (Income) Margin = = 10.8% Revenue 600 FOR 2016 Operating 223 Operating Margin = 31.0% Revenue 720 Net Income 56 Net (Income) Margin = = 7.8% Revenue 720 b. Calculate the Return on Equity. Net Income 65 Return on Equity = = 40.6% Shareholders Equity 160 Net Income 56 Return on Equity = = 29.7% Shareholder Equity 189 c. Based only on your answer in a) what might be driving the year-over-year change of the RoE? ROE is Declining year over year. Net Margin is decreasing (worsening) y-o-y so this must be driving the decline in ROE. If our Net Margin is declining our costs must be growing faster than our Revenues. Upon further inspection, our Operating Margins actually improved marginally, 30% growing to 31%. Therefore, it must be our costs below the Operating Expenses line that are growing faster than Revenues, maybe we had a loss on discontinued operations, or cost from Certain Items