reserve a, b, c, d, e for Complex;

theorem :: REAL_2'55_1
  c <> 0 implies a / b = (a / c) / (b / c)
proof
  assume c<>0;
  hence a/b=(a*c")/(b*c") by Lm10
    .=(a/c)/(b*c") by XCMPLX_0:def 9
    .=(a/c)/(b/c) by XCMPLX_0:def 9;
end;
