can you please give some formulas and steps to solve this exercise in excel?

Financials. The tab data in the file financials.xlsx shows monthly revenues $($Sales$)$ and expenses of three divisions $($software$,$ advertising, and hardware$)$ of a company, over multiple years. Obtain consolidated annual revenue & expense statement for the company $($all three divisions taken together$)$ for each year on file. What is the average profit margin of the company $($ratio of the sum of all expenses to Sales$)$ and its trend over time? Round the reported percentages to the whole percentage point. Source of data: financials.xlsx Required output: A number $($average profit margin$)$; a series of annual numbers $($average profit margins by year$).$