Well, first you need to clarify the objective :)
If this question is during an interview, we both know what you should say your objective is: "To be clear, my objective here, first and foremost, is to fulfill the duties of my job as I know what I'm signing up for. My secondary objective is to ensure my friend has a good bachelor's party"
Then, you need a framework.
Bucket A is how to fulfill your work duties efficiently
Bucket B is how to meet the needs of your friend.
If you're "smart" you tell the interviewer "I have to work 25 hours to get 100%, and 15 for 80%. I would check with the Partner whether we're looking for 80% or 100% for his/her review. I also need to be sure I have enough sleep to perform during the week"
You can realize that, between Fri and Mon you must have 24 hours of sleep, leaving you with 41 waking hours (65 total hours from 4pm Fri to 9am Mon minus the 24 hours sleeping).
So, actually, this problem isn't that hard...you can do both :) But, you would likely need to breakdown how you setup the party for success (contact your friend's other friends), plan your Sat+Sun working days on the Friday, then attend the party but stay sober etc.
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They did ask;)
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