[0.85-(9/16-0.15)]×8/21

问题描述:

[0.85-(9/16-0.15)]×8/21

[0.85-(9/16-0.15)]×8/21
=[(0.85+0.15)-9/16]×8/21
=(1-9/16)×8/21
=7/16×8/21
=1/6