reserve x1, x2, x3, x4, x5, x6, x7 for set;

theorem Th22:
  for a being Rational, b being irrational Real st
  a <> 0 holds b / a is irrational
proof
  let a be Rational, b be irrational Real;
  assume
A1: a <> 0;
  assume b / a is rational;
  then reconsider c = b / a as Rational;
  c * a is rational;
  hence thesis by A1,XCMPLX_1:87;
end;
