Error of the Intercept with 2 Idependent Variables

#1
I'm building a multiple regression model from scratch in Excel with 2 independent variables (IVs). I'm cross-checking the results with the Excel Analysis Toolpak.

Thanks mostly to 2IV Regression instructions posted at a U. of S. Florida website, I have successfully duplicated the Toolpak output, including the standard errors of the IVs. However, I cannot for the life of me figure how to calculate the error of the Intercept. Can anyone walk me through this? I have attached my data, model and Excel results for reference. I just need to know the math behind the RED number.

Thanks in advance!
Chris

P.S. I tried to attach the Excel file instead of a pic...but I guess it's not allowed (sorry!).
 

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