29*9/28
=（28+1）*9/28
=28*9*28+9/28
=9+9/28
=9又9/28
9/17*86-9/17
=9/17*（86-1）
=9/17*85
=45
36*(2/9+1/4-1/12)
=36*2/9+36*1/4-36*1/12
=8+9-3
=14
3/8+5/8*24
=3/8+15
=15又3/8