（6分之1-9分之1）×18
=1/6x18-1/9x18
=3-2
=1
1.2+9.8+7.22+10.2
=(9.8+10.2)+(1.2+7.22)
=20+8.42
=28.42
9-0.64-0.36
=9-(0.64+0.36)
=9-1
=8
12分之3÷6分之3÷12分之5×4分之3
=(3/12÷3/6)x(3/4÷5/12)
=2x9/5
=18/5
如果本题有什么不明白可以追问,