22/7×21/22×(22/7-22/3)×(-7/22) 先用交换率
=22/7*(-7/22)*21/22*(22/7-22/3)
=(-1)*(21/22*22/7-21/22*22/3)
=(-1)*(21/7-21/3)
=(-1)*(3-7)
=(-1)*(-4)
=4
22/7×21/22×(22/7-22/3)×(-7/22) 先用交换率
=22/7*(-7/22)*21/22*(22/7-22/3)
=(-1)*(21/22*22/7-21/22*22/3)
=(-1)*(21/7-21/3)
=(-1)*(3-7)
=(-1)*(-4)
=4