18÷﹙3.2－1.7﹚－1.5
=18÷1.5 - 1.5
=18÷(3/2) - 1.5
=18×(2/3) - 1.5
=12 - 1.5
=10.5
4/5－﹙4/5+1/4﹚÷3
=4/5－﹙16/20 + 5/20﹚×(1/3)
=4/5－﹙21/20﹚×(1/3)
=16/20 - 7/20
=9/20
5/9+8/15÷3/10－1/6
=5/9+ 8/15×(10/3)－1/6
=5/9+ 16/9－1/6
=21/9 - 1/6
=7/3 - 1/6
=14/6 - 1/6
=13/6
=2又1/6