@Carl Love I have just find out this solution is not the only one. I use avoid={} function and got another one which satisfy my request for positive solutions. After second iteration with avoid{} I couldn't get explicit answer. Is there any way to get all solutions ant to be sure they are complete. 

P.S. I forgot to write in the first post additional request. Second derivative of Fw use to be positive for given solution. Both solution which I got satisfy that request. This is maple file equ_sys.mws. Thanks

@Carl Love Thanks a lot. I didn't expect such fast answer. It works now. I'm not sure if it's the only solution of the equations system. I hope it is. Thanks again.