Let's assume that you source query includes your data table with a Weekday column (containing Mon, Tue, Wed, etc.), an Hours column, a Rate column (which might be from another table that is linked through an employee account number to the main table). Create a grouping query something like this using the query builder:
SELECT [Weekday], Sum[Hours] AS TtlHrs, First[Rate] AS HrlyRate, (*[TtlHrs]*[HrlyRate]) AS TotalCost FROM [SourceTable] GROUP BY Weekday;
Obviously you will also include criteria to limit the date range, assuming your source data table includes a date column.