How to Total the number of hours-worked on each date?

Hello, people,

I studied the SUBTOTAL thing, but... maybe that's not what should be used here?

In the attached sample file, I want the Total of hours worked on each day, in column P.
That is,... when column B changes, put a total of the column H hours in column P.

In the file, columns O and P and Q were manually created.
Column O shows the number of time-spans (rows) for any certain date.
Column P is what I want to automatically calculate...
it shows the total number of hours worked on that date.
Column Q shows the overtime $amount that I should get (at the $16.5/hour rate,
with time-&-a-half for hours 8.01 thru 10, and double-time above 10 hours.)

HOW to automatically calculate column P?

Thanks, in advance.

Mark53