reserve a,b,c,d for Real;
reserve r,s for Real;

theorem
  c < 0 & b < 0 & a < b implies c/a < c/b
proof
  assume that
A1: c < 0 and
A2: b<0 and
A3: a<b;
  a">b" by A2,A3,Lm31;
  then a"*c < b"*c by A1,Lm24;
  then c/a<b"*c by XCMPLX_0:def 9;
  hence thesis by XCMPLX_0:def 9;
end;
