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

theorem
  a <= 0 & a <= b implies b/a <= 1
proof
  assume a <= 0;
  then per cases;
  suppose a = 0;
    then a" = 0;
    then b*a" = 0;
    hence thesis by XCMPLX_0:def 9;
  end;
  suppose
A2: a < 0;
    assume
A3: a <= b;
    assume b/a > 1;
    then b/a*a < 1*a by A2,Lm24;
    hence thesis by A2,A3,XCMPLX_1:87;
  end;
end;
