 reserve x for Real,
    p,k,l,m,n,s,h,i,j,k1,t,t1 for Nat,
    X for Subset of REAL;

theorem
  for i,j,h being natural Number holds i <= j implies i * h <= j * h
proof
  let i,j,h be natural Number;
  0 <= h by Th2;
  hence thesis by XREAL_1:64;
end;
