1.
1又4/17乘2又2/3减3/4的差加15又1/12除以7/21
=(5/4*8/30)-3/4+(181/12*21/7)
=(5/1*2/30)-3/4+(181/4*7/7)
=10/3-3/4+181/4(通分)
=(40-9+543)/12
=574/12=287/6
2.41又1/3*3/4+51又1/4*4/5+61又1/5*5/6
=(124/3*4/3)+(205/4*4/5)+(306/5*6/5)
=(124/3*4/3)+(41/1*1/1)+(306/5*6/5)
=(496/9)+41+(1836/25)(通分)
=(12400+9225+16524)/225
=38149/225