Question

11．脱式计算，能简算的要简算．

2.55÷1.7-0.59	3.7×7.9+3.7×2.1	（2-0.4）÷$\frac{8}{15}$
$\frac{8}{9}$÷0.625÷$\frac{5}{4}$	$\frac{3}{7}$×（$\frac{4}{5}$-$\frac{2}{3}$）÷$\frac{5}{14}$	$\frac{3}{4}$×93+6×0.75+75%

Answer 1

分析 算式①、③、④、⑤根据四则混合运算的运算顺序计算即可．
算式②⑥可据乘法分配律进行计算；

解答 解：①2.55÷1.7-0.59
=1.5-0.59
=0.91

②3.7×7.9+3.7×2.1
=3.7×（7.9+2.1）
=3.7×10
=37

③（2-0.4）÷$\frac{8}{15}$
=1.6×$\frac{15}{8}$
=3

④$\frac{8}{9}$÷0.625÷$\frac{5}{4}$
=$\frac{8}{9}$×$\frac{8}{5}$×$\frac{4}{5}$
=$\frac{256}{225}$



⑤$\frac{3}{7}$×（$\frac{4}{5}$-$\frac{2}{3}$）÷$\frac{5}{14}$
=$\frac{3}{7}$×$\frac{2}{15}$×$\frac{14}{5}$
=$\frac{4}{25}$

⑥$\frac{3}{4}$×93+6×0.75+75%
=0.75×（93+6+1）
=0.75×100
=75

点评 完成本题要注意分析式中数据，运用合适的简便方法计算．