Calculating time/ days for each activity in a process based on a critertira from another column

Hi,

I posted a similar case last week however it is actually a bit more complicated:

I need to figure out the time (in days) between different “Transactions” within each Booking number in the below table. For each Booking number there might be several rows with the same Transaction and in that case the measure needs to pick the last one.

E.g. Booking number 123 – I want to calculate the number of days from Order is created (Timestamp 01.08.2018) until Transaction “Completed” (Timestamp 05.08.2018). In this case there is two rows with “Completed” and the measure must pick the last one.

This might be a part of the solution...?

https://community.powerbi.com/t5/Desktop/How-to-find-the-last-timestamp-in-a-column-for-a-certain/m-p/499255#M232871

This solves partially the problem, calculating the time from “Start to finish” – in addition the calculation must split that number of days into each booking, and taking into consideration the last one if there is several rows with the same Transaction (e.g Completed for booking nr. 123 =pick the last of the two "Completed"

Appreciate any suggestion to solve this!

Regards

Amund