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)运用乘法分配律简算;
(2)先把除法变成乘法,再运用乘法分配律简算;
(3)先同时运算小括号里面的乘法和除法,再算小括号里面的减法,然后算括号外的除法,最后算括号外的减法;
(4)先去掉小括号,然后运用加法交换律简算,最后算括号外的乘法;
(5)根据比例的基本性质解方程.
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.