Calculate Duration in Hours & Minutes, and Decimal

Hi - Newbie here - so I have a newbie question!

I have two TIME fields: START TIME and END TIME on my App.
I need to express the difference (duration) between these time points in two different ways:

Example: START TIME = 08:00AM and END TIME = 09:30AM

Duration Column A = 1 Hr 30 m.
Duration Column B = 1.5

Can someone advise how I can achieve this, please?

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