①2.5×1.67×0.4
②2.1÷0.35+0.45
③9.65×4.9+9.65×6.1-9.65
④20.4÷8.5×(6.5-5)
217﹣18= ×= 3÷= 0.78+0.32=
32﹣0.25= 3﹣= 200×3.6= +×5=