解:(1)195.6×18-195

×8,
=195.6×(18-8),
=195.6×10,
=1956;
(2)(1

+2

)÷

,
=(

+

)×2,
=

×2+

×2,
=

+5,
=7

;
(3)2.1-(0.27×

-19÷700)÷

,
=2.1-(

-

)÷

,
=2.1-

÷

,
=2.1-1,
=1.1;
(4)

×[

-(

-0.25)],
=

×[

+

-

],
=

×(1-

),
=

×

,
=

;
(5)

:

=40:x,

x=

×40,

x=

,

x

=


,
x=15.
分析:(1)運(yùn)用乘法分配律簡算;
(2)先把除法變成乘法,再運(yùn)用乘法分配律簡算;
(3)先同時(shí)運(yùn)算小括號(hào)里面的乘法和除法,再算小括號(hào)里面的減法,然后算括號(hào)外的除法,最后算括號(hào)外的減法;
(4)先去掉小括號(hào),然后運(yùn)用加法交換律簡算,最后算括號(hào)外的乘法;
(5)根據(jù)比例的基本性質(zhì)解方程.
點(diǎn)評(píng):考查了運(yùn)算定律與簡便運(yùn)算,四則混合運(yùn)算.注意運(yùn)算順序和運(yùn)算法則,靈活運(yùn)用所學(xué)的運(yùn)算律簡便計(jì)算.