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

theorem :: REAL_2'79
  b <> 0 implies a * c = a * b / (b / c)
proof
  assume
A1: b<>0;
  thus a*c =a*1*c .=a*(b*b")*c by A1,XCMPLX_0:def 7
    .=a*b*(b"*c)
    .=a*b*(b*c")" by Lm11
    .=a*b/(b*c") by XCMPLX_0:def 9
    .=a*b/(b/c) by XCMPLX_0:def 9;
end;
