A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
=SUMIF(START:END!F5:F23,">0",START:END!K5:K23)
You can use SUM() to cover multiple cells within a single worksheet or a single cell through multiple worksheets, but you cannot use it to SUM() multiple cells through multiple worksheets.
Click the START worksheet's name tab to activate it then hold the Shift key down and click the FINISH worksheet's name tab. In a cell that is blank to all of the selected worksheets put in this formula,
=SUMIF(F5:F23, ">0", K5:K23)
That will place the formula on that cell (e.g. AA1 for example) in all of the worksheets you've selected.
On your summary page, you can now use SUM() to drill through the worksheets with,
=SUM(START:FINISH!AA1)