reserve a,b,c,d for positive Real,
  m,u,w,x,y,z for Real,
  n,k for Nat,
  s,s1 for Real_Sequence;

theorem Th3:
  a<b implies 1<(b+c)/(a+c)
proof
  assume a<b;
  then a+c<b+c by XREAL_1:8;
  hence thesis by XREAL_1:187;
end;
