0.75÷0.25+
×
(8.6×0.5-
)÷12
÷[
-(
+
)][800×(1+25%)-360×1.5]÷25%
15-[
+(2.5-
)]÷0.125.解:①0.75÷0.25+
×
,=
×4+
×
,=3+
,=3.5;
②(8.6×0.5-
)÷12,=(4.3-3.1)÷12,
=1.2÷12,
=0.1;
③
÷[
-(
+
)],=
÷[
],=
÷
,=
×
,=1
;④[800×(1+25%)-360×1.5]÷25%,
=[800×
-360×1.5]×4,=[1000-540]×4,
=460×4,
=1840;
⑤15-[
+(2.5-
)]÷0.125,=15-[
+
]
,=15-[
]×8,=15-
,=15-12,
=3.
分析:这6个算式都按照分数的四则混合运算的顺序进行计算,有括号的先计算括号内部的,再计算括号外部的,第⑥个式子再计算时多留心计算即可正确解答.
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.