I need help creating the query. I dont know how to create the equation you need for the new field name called number of advisees. please help with equation!!

Query 4 and Report: Create a query that shows the advisors, their departments, and the number of advisees for each advisor. The fields you need to add in this query are Department 1D, Department Name; Advisor ID, Advisor Last Name, Rank, Date Joined, and a new field named Number of Advisees, which counts the number of advisees per advisor. Save this query as Query for Report. Create a report based on the query Query for Report. (You can use the Report Wizard or the Report option). Group the fields by Department 1D then within each group, sort by Date Joined from newest to oldest. Set the page layout for Landscape. In the design or layout view, format the report so that Deportment ID and Department Nome appear together on the same line. Add a grand total for the Number of Advisees field that calculates the total number of students for all advisors. Format the report as needed so all fields and labels are visible and are left of the vertical dotted line. Make your report appear as below, deleting any totals or labels not shown. Assign the title of Advisors Report and save the report as Advisors Report