Average only the 1st item when there are duplicates in a list

[JungleJme]

Hi everyone,

I have a set of data which lists the details of work orders. A work order can have several segments (say £1000 for Parts, £2000 for labour etc...) however, as a whole the work order will only be so many days old. So i need to average out how old the work orders but avoid double counting duplicate entries in the calculation.

I have attached an example which illustrates my problem and desired result. I've been scratching my head on how to achieve this for some time now, any help would be greatly appreciated!

Thanks in advance,

J