Creating a family budget worksheet!

I am trying to do a money tracking sheet for my household budget. I want to have a sheet were I can put each transaction during the month. I have money alcoated to certain things throughout the month. When i put in a new trabsaction I want to be able to select a value from a drop down menu (food, kids epepences, fun money, ect). After i seleft the drop down and put a money value in the next cell I would like it to subtract from the amount i have at the top of the sheet.

Example,

lets say i have a 500 dollar a month food budget. I put 500 at the top of the sheet and label it food money. When i out in a transaction below and select food money from the drop down and a money value I would like it to subtract form the 500 up top. Is this possible?