（1）36分之105乘49分之39乘91分之63
=(105/36)*(39/49)*(63/91)
=(15/4)*(3)*(1/7)
=45/28
=1又17/28
（2）4分之5乘8分之1乘16
=(5/4)*(1/8)*16
=(5/4)*2
=5/2
=2.5