159*（353535/535353）-105又103/104

159*（353535/535353）-(105+103/104)
=159*（35*10101/53*10101）-(105+103/104)
=105-105-103/104
=-103/104
9999*1111+3333*6666
=9999*1111+3333*3*2222
=9999*(1111+2222)
=(10000-1)*3333
=33326667
1/（2*5）+1/（5*8）+1/（8*11）+1/（11*14）+1/（14*17）+1/（17*20）
=(1/3)*(1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+1/17-1/20)
=(1/3)*(1/2-1/20)
=(1/3)*(9/20)
=3/20
7285*（12+7/8）+2742*128.75
=7285*(103/8)+2742*(515/4)
=7285*(103/8)+2742*(1030/8)
=(7285+2742*10)*(103/8)
=(7285+27420)*(103/8)
=34705*103/8
=3574615/8