Availability calculation

Hello everyone,

I'm beginner at power BI and I have absolutely no experiences with DAX. 
I'm looking here for a help with creating a calculation of machine availability.
I need to count minutes in day and set it as 100% availability for every day in week, then I would need to deduct minutes where macine has not been working and adjust the % availability to it to the specific day/week.
Is here someone who could possibly help me with this one?

I have tried to google it but no luck so far.
I will be happy about every answer/advice 

Thank you in advice ❤️