hello community

can community guide me on this:
Example that the difference of time is 10:00AM to 1:00PM = 3:00 hr
I used the format [h]:mm to sum the total hours and
I wanted to have the total hours multiply by say, $15.00 (which is the
hourly rate) but
my output result is 1.875 instead of $45.00
the working is (3:00 * 15) am I correct to use this formula ??

can community assist me on this ?

thanks for the help :)
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oldLearner57