14/11乘10/7乘33/8
=20/11乘33/8
=15/2
85乘84/5
=17乘84
=10乘84+7乘84
=840+588
=1428
5/4减5/4乘6/5
=5/4 乘(1-6/5)
=-5/4乘1/5
=-1/4