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

theorem :: REAL_2'70
  (a * b) / (c * d) = (a / c * b) / d
proof
  thus a*b/(c*d)=1/c*(a*b/d) by Lm15
    .=1/c*(a*b)/d by Lm8
    .=1/c*a*b/d
    .=a/c*b/d by Lm14;
end;
