reserve X for set;
reserve a,b,c,k,m,n for Nat;
reserve i for Integer;
reserve r for Real;
reserve p for Prime;

theorem Th64:
  m,n are_coprime implies a*n+m,n are_coprime
  proof
    a*n+m,m are_congruent_mod n;
    hence thesis by WSIERP_1:43;
  end;
