-6*(3分之1-2分之1)
=-6×(1/3-1/2)
=-6×(-1/6)
=1
(3分之1-7分之5-5分之2)*105
=(1/3-5/7-2/5)×105
=(35/105-75/105-42/105)×105
=(-82/105)×105
=-82