解:
(1)1÷

×

,
=

×

,
=

;
(2)7684×101-7684,
=7684×(101-1),
=7684×100,
=768400;
(3)

÷25%×

,
=1×

,
=

;
(4)

×2÷

×2,
=(

÷

)×(2×2),
=1×4,
=4;
(5)9

-(3

+0.4),
=9

-0.4-3

,
=9-3

,
=5

;
(6)31.625-40÷16×2,
=31.625-2.5×2,
=31.625-5,
=26.625;
(7)(1-0.75)×(3.9+2.25÷2.5),
=0.25×(3.9+0.9),
=0.25×4.8,
=1.2;
(8)2

÷[5

-4.5×(20%+

)],
=2

÷[5

-4.5×

],
=2

÷[5

-2.4],
=2

÷3

,
=

;
(9)

,
=[1÷

-2

]×

,
=[

-2

]×

,
=5

×

,
=

.
分析:(1)先算除法,再算乘法;
(2)根据乘法分配律进行计算;
(3)先算除法,再算乘法;
(4)根据乘法交换律和结合律进行计算;
(5)根据连减的性质进行计算;
(6)先算除法,再算乘法,最后算减法;
(7)先算小括号里面的,再算乘法;
(8)先算加法,再算乘法,再算减法,最后算除法;
(9)先算加法,再算除法,再算减法,最后算乘法.
点评:此题主要考查分数、小数和整数的四则混合运算的运算顺序和应用运算定律进行简便计算.