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

theorem Th83:
  0 < b & c < a*b implies c/b < a
proof
  assume that
A1: b>0 and
A2: a*b>c;
  a*b/b>c/b by A1,A2,Lm26;
  hence thesis by A1,XCMPLX_1:89;
end;
