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

theorem
  0 < b & b < -a implies a/b < -1
proof
  assume
A1: b>0;
  assume
A2: b < -a;
  assume a/b >= -1;
  then a/b*b >= (-1)*b by A1,Lm12;
  then a >= -b by A1,XCMPLX_1:87;
  hence thesis by A2,Th26;
end;
