Button in Excel for Date conversion + Formulas to calculate subtotals with different criteria

Dear Programmer, Your task is to work on the excel spreadsheet attached, and create the button and formulas needed. Task 1 Program the blue button in the Subtotals tab, so it converts all dates in the Start column of the Available Time tab (highlighted in yellow) to Excel-readable format (retaining full date and time information). We need this because in task 2, you will need to perform calculations on this column, and with the current format, the cell values are dead, they are treated like text by Excel. Macros and Visual Basic are allowed for this task Task 2 You will work on the Subtotals Tab, and you will supply the formulas for the cells that are highlighted in yellow (main calculations) and light yellow (same formulas that the yellow ones, simply adapted for the next week time frames). You will see the description of what you should calculate, in each cell. No macros or visual basic allowed for this task. Simply use formulas that I can edit in the cells if I need to in the future. I have translated to English all the main column headers so you will not have problem even if the spreadsheet is in Spanish. I have explained in the spreadsheet, in English, exactly what cells and cell ranges must be evaluated. This is an easy job for a person that is expert in Excel. If you have experience integrating excel with google calendar (e.g. invoking the google calendar API from excel, getting or posting data to or from it), please let me know as I have other tasks in mind for future projects that I may ask you to do if these first 2 tasks go well. Thanks Walter