3/7÷(5/7-3/7-1/5)=3/7÷(2/7-1/5)
=3/2-15/7=-9/14
(6分之5-4分之3)÷(12分之5×5分之9)
=(6分之5-4分之3)÷3/4
=5/6÷3/4-1=1/9