How to Index and then Offset and then Add the outcomes.

So i have a very simple expenses table as attached, and in a random cell, I want to be able to make it Search A:A for the term "Food" which is one of the validation list options, and then offset, 0,2 to the "out" column, and then all of them up.

So in simple terms I want to add up the total Cost of "food" so the answer as the table stands at the moment will be £20. but then i want the ability to add another "food entry" and that be included for for instance if i have another food entry worth £5 I want my cell to change to £25.

Any help will be much appreciated!