Working hours VS lead times

Hi everyone,

I have a database which captures requests that I receive with starting dates such as: 06-05-2019 6:50:11 AM
Then, I have a workflow with different steps to complete the requests. For each of the steps, my system captures the time I spent on each of them in seconds:
Step 1: 751 seconds
Step 2: 8967 seconds
Etc.

The problem is that there are office hours that the system does not take into consideration (from 8am to 12, from 1pm to 5pm, from Monday to Friday).
If I receive a request on Thursday 4pm and that the step 1 is completed on Monday 10am, the system considers the remaining 8 hours of Thursday + 72 hours for Friday, Saturday & Sunday + 10 hours for Monday = 90 hours of work in total.
So I would like to extract the actual number of hours which were needed, meaning 1 hour on Thursday, 8 hours on Friday, and the 2 hours on Monday = 11 hours in this example.

Any idea of a formula which could help me?

Many thanks!

Attach a sample workbook. Make sure there is just enough data to demonstrate your need. Include a BEFORE sheet and an AFTER sheet in the workbook if needed to show the process you're trying to complete or automate. Make sure your desired results are shown, mock them up manually if necessary.

Remember to desensitize the data.

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