reserve a,b,c for positive Real,
  m,x,y,z for Real,
  n for Nat,
  s,s1,s2,s3,s4,s5 for Real_Sequence;

theorem
  (a+b+c)/3>=3-root(a*b*c)
proof
  (a+b+c)/3>=(3*(3-root(a*b*c)))/3 by Th15,XREAL_1:72;
  hence thesis;
end;
