求小学五年级下册分数简便计算要有点难度、要30道以上

4/7+1/14-1/2
=8/14+1/14-7/14
=2/14
=1/7
5/3-3/8-5/8
=5/3-(3/8+5/8)
=5/3-1
=2/3
3/5+3/11+7/5+11
=(3/5+7/5)+11+3/11
=2+11+2/11
=13又2/11
3/4-｛5/6-1/3｝
=3/4-（5/6-2/6）
=3/4-1/2
=3/4-2/4
=1/4
12.75—17分之5＋1又4分之1
=12又3/4+1又1/4--5/17
=14-5/17
=13又12/17
（6分之5—4分之3)÷（4分之1＋6分之1）
=1/12÷5/12
=1/12X12/5
=1/5
33/37×36
=33/37×（37-1）
=33/37×37-33/37×1
=33-33/37
=32又4/37
33/37×38
=33/37×（37+1）
=33/37×37+33/37×1
=33+33/37
=33又33/37
157*23/156
=(157-1)*23/156+23/156
=156*23/156+23/156
=23+23/156
=23又23/156