Hi and thanks for your help in advance!!!  

  I am trying to do the angled cut shown in the attached drawing in red.  The problem I'm having is I don't know how to do it so the cut out section ends and then goes up at a 45 degree angle.  I tried doing it with and extruded cut of the rectangular shape from the top and then doing the triangular cut from the side.  It doesn't look right and then it has an error when I try to flatten it.  I also included a closer screen capture of section E-E as well for clarity.

Any help will be greatly appreciated!!!?

Chris