Getting number of days using a Data Slicer Picker does not give equal results

[zyeet]

I am trying to get the number of days between two dates to use it in a calculation to estimate a truck's delivery capacity, that goes like this:  5000 gallons * 3 trips * No. of Days.

I have been successful so far in getting the number of days between two dates using a date slicer, but one of my rows is giving me 90,000 instead of 105,000 since that particular truck started delivery from Day 2:

The problem is that I want the capacity to be estimated between certain dates (exact number of days), and not just from the date the truck actually started delivery, for example a week - 7 days, or a month - 30/31 days. I understand that using the date column from my table means that it is looking at each truck individually, but I only want the days from a range irrespective of deliver or not as I am trying to automate this report with daily data updates.

Below is an excerpt from the table and the measure for the Delivery Capacity: 

[lbendlin]

Please provide sample data (with sensitive information removed) that covers your issue or question completely, in a usable format (not as a screenshot). Leave out anything not related to the issue.
https://community.fabric.microsoft.com/t5/Community-Blog/How-to-provide-sample-data-in-the-Power-BI-...
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https://community.fabric.microsoft.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447...