in ref to earlier thread

http://www.mathhelpforum.com/math-he...tml?pagenumber=

I have stumbled upon a question which poses an identical problem but not in the form of an exam question therefore i suppose you could sketch it although from the simplicity of it i doubt this is really necessary.

If someone could show how they obtained this answer,,,and then give a valid proof to a valid method for my previous thread i'd appreciate the help,,

Q: Random variables x and y have jonint density function exp(-x-y) x.y>o

findp(x>y) answer back of book is 1/2