Can anyone help with the Five Executives logic game from the December 2008 preptest 56? I think I've got the set up, but I'm finding the questions impossible without like 10 minutes of work on each question (basically running every scenario). I can not seem to work them out quickly at all. Some of them I'm not even sure I can follow all the way to the answer. What am I missing? I am having the most trouble with #19, 20, 21 and 23. Thanks for any help.