(1)4.07－350÷70×0.24
=4.07-1.2
=2.87；
(2)[2分之3－(5分之4－8分之5)]÷20分之7
=（3/2）×20/7-(4/5)×20/7+(5/8)×20/7
=30/7-16/7+25/14
=14/7+25/14
=53/17
(3)4÷5×5分之13＋7÷5×5分之4＋1÷4分之5
=52/25+28/25+4/5
=80/25+4/5
=20/5
=4
如果本题有什么不明白可以追问,