Happy birthday!
You might want to consider getting a copy of OO beta 2.0. Its much shinir.

Or at least the latest stable release, 1.1.5.
Anyways... To make a formula in a column, enter something like this in cell C2:
=B2/4
Bill total would get:
=SUM(C2:C5)
You might mant to make the Phonecalls data be a single row for better readability.