Hello - I'm working on a project I can't wrap my brain around this and am hoping to get some help here.

We have a scanning project that involves the 3 tasks of prepping, scanning and reassembling files.

Given the following information:

Total Files = 650
Employees = 5
Number of Hardware Scanners = 3

Prepping 3 files per hour
Scanning 5 files per hour
Reassembling 3 files per hour

What is the formula/algorithm to determine how to best utilize the staff to get all 650 files prepped, scanned and reassembled in the least amount of time? i.e. # of staff performing each task for X period of time/# of files before shifting staff to other tasks.

Any help would be greatly appreciated. I am working on this in excel now.
Thank you!