Determine all possible values of

[ a/(a+b+d) + b/(a+b+c) + c/(b+c+d) + d/(a+c+d) ]  for positive reals a, b, c, d.

 

REQUEST - THIS POST IS NOT FOR PEOPLE WHO HAVE SOLVED THIS Q. BEFORE OR HAVE AN IDEA FROM WHERE TO GET THE SOLUTION ( BY SOME UNKNOWN REFERENCES  ..............  )

 

NOTE : I HAVE POSTED THE SOLN. ON PAGE 4 OF THIS POST SINCE NOBODY WAS ABLE TO SOLVE IT .

 

IF ANY NEW USER IS INTERESTED IN SOLVING IT , PLZ. DONT SEE PAGE 4 ( B HONEST YAAR) . 20 RATES ARE STILL UP FOR GRABS..............