iWorks Numbers: how set an if/then condition?

Using numbers, I want to set up a formula to do the following:

* If Column E = "Y," then subtract the value of column I from the value of column L.

* If Column E is anything but a "Y", return a value of "0".


I've never had to deal with a conditional in a formula before, and my searches keep revealing tips for conditional formatting.

Any help would be appreciated. Thanks.


UPDATE: Nevermind. I figured it out.