How to Mutiply and Subtract Cells?

I am trying to do a overtime calculator.
If an employee has a limit of a certain amount of money to use in overtime I want them to be able to keep up with it simply by typing in the number of hours they work each week and getting excel to subtract the amount from thier balance.
If this possible or do I need another program?
Thanks for any help?

Hello

See if attached file helps u. See formulas in green coloured cells.

First of all, I would recommend getting rid of merged cells.
If you want it to look nice use " center across selection" formatting instead of merged cells

Next, using labels you can have a simple formula to calculate the reminder of the overtime amount ( see attached)

You have to activate labels via Tools - Options - Calculations - Accept labels in formulas

I will study the examples made and try to learn something, your responses are appreciated.