reserve z,z1,z2,z3,z4 for Element of F_Complex;

theorem
  z2 <> 0.F_Complex implies (z1 / z2)*' = (z1*') / (z2*')
proof
  reconsider z19=z1,z29=z2 as Element of COMPLEX by Def1;
  assume
A1: z2 <> 0.F_Complex;
  then
A2: z2*' <> 0.F_Complex by Th48;
  z19 / z29 = z1 / z2 by A1,Th6;
  hence (z1 / z2)*' = (z19*') / (z29*') by COMPLEX1:37
    .= (z1*') / (z2*') by A2,Th6;
end;
