Formula Help! New Column (If this is not blank, use this, else)

Hello!!

First time poster to this forum! HELPP.. I am struggling with this formula..  I have these three columns:

Scheduled End Date     Extended End Date      Actual End Date

It is like a funnel, so everyone has scheduled end date filled out, and then a good chunk have extended end date, and then only a few have actual end date -- 

I want to add a new column with an if statement, that if there is an actual end date, use that, if not then if there is a extended end date, use that date, else use schedule end date

Can someone help me with writing this formala exactly so I can copy paste? Thanks in advance!

Hannah