I am trying to figure out how to write a formula to do the following:

Let's say in Column A I enter in character data (Item 1, Item 2, Item
3, etc) and in Column B I enter in numerical data (25.50, 52.30,
43.02, etc). What I want to be able to do is:

If the data in Column A = Item 1, take the Sum of the adjacent data in
Column B.

So if my spreadsheet looks like this:

Item 1 25.50
Item 2 52.30
Item 1 43.02

and I run the formula above, it would output this: 68.52

If anyone could help me with this Excel formula, that would be great.