[7-(0.5*9.5+3*6分之1)】*21分之8
问题描述：
[7-(0.5*9.5+3*6分之1)】*21分之8
答
[7-(0.5*9.5+3*6分之1)】*21分之8
=7×21分之8-(1/2×19/2+1/2)×21分之8
=3分之8-1/2×21/2×8/21
=8/3-2
=2/3
答
[7-(0.5*9.5+3*6分之1)】*21分之8
=(7-4.75+0.5)*21分之8
=4分之11*21分之8
=21分之22