a. You will need to merge all four data tables.b. You will need a intermediary step for calculation of total sales per order before you aggregate sales by states.c. Be aware of what variables to include, when to drop variables, and when to remove duplicated observations.d. To calculate unique number of values by group, you will need to use function egen=nvals(). You have to install the package containing this function before you can use it. You can install the package by typing the following statement in to your command window:ssc inst egenmoreYou only have to install the package once per Stata copy.