Pilot logbook 90 day current till formula

[JakeTehMuss]

Hi Everyone, So attached is a sample logbook. In the Dashboard TAB I need to know what date my 3rd to last landing was on each type of aircraft. In Cell 'AG5:AH17 it needs to display the date plus 90 days. So for example 8 nov 17 was my 3rd to last landing in a DA42 at night. So i would become uncurrent (unable to fly passengers at night) in that aircraft on the 06-02-18. The 3rd to last in C172 at night was on the 16-12-17 = 16-03-18...

I have hit a wall with this... Please Help...

https://1drv.ms/x/s!Agcz5VJd-EDIo2FzDnju9gYZ3i8Y


Also to clarify im wanting a formula not a Macro/vga. Im open to making helper cells if required.

Thanks in advanced and I hope you have fun.

 

[mole999]

maybe =LOOKUP(2,1/(C:C<>""),C:C)-3

 

[JakeTehMuss]

Im having trouble getting that =lookup working. So i've tried a different approach.

The cells im having trouble formatting are =DASHBOARD!AG5:AH17
It needs to show date since 3rd to last landing.

I have tried following this www.superuser.com/questions/744201/excel-calculate-pilot-currencies

But getting confused with where ive gone wrong Ive made the helper cells in AQ:AS
Any other tips would be greatly appreciated.

 

[mole999]

the offering related only to column C, it should be able to be placed in any other cell, excluding C