三、计算。(共22分)
1. 直接写出得数。(6分)
$0.4×0.2=$         $9 - 0.9=$         $7.2÷0.4=$         $3÷7=$
$\frac{2}{5}+\frac{1}{3}=$         $\frac{1}{5}-\frac{1}{6}=$         $24÷\frac{3}{4}=$         $\frac{7}{9}×45=$
$8.75-(0.75 + 3.4)=$         $(3+\frac{3}{20})×5=$
$1÷\frac{2}{3}×\frac{3}{2}=$         $\frac{3}{4}+\frac{1}{2}÷\frac{1}{2}=$

$0.4×0.2 = 0.08$
$9 - 0.9 = 8.1$
$7.2÷0.4 = 18$
$3÷7 = \frac{3}{7}$
$\frac{2}{5} + \frac{1}{3} = \frac{11}{15}$
$\frac{1}{5} - \frac{1}{6} = \frac{1}{30}$
$24÷\frac{3}{4} = 32$
$\frac{7}{9}×45 = 35$
$8.75 - (0.75 + 3.4) = 4.6$
$(3 + \frac{3}{20})×5 = \frac{63}{4}$
$1÷\frac{2}{3}×\frac{3}{2} = \frac{9}{4}$
$\frac{3}{4} + \frac{1}{2}÷\frac{1}{2} = \frac{7}{4}$

2. 解方程。(4分)
$2x + 2.7 = 24.7$ $x-\frac{2}{3}x=\frac{1}{3}$

解方程 $2x + 2.7 = 24.7$
解：
$2x = 24.7 - 2.7$
$2x = 22$
$x = 22 ÷ 2$
$x = 11$
解方程 $x - \frac{2}{3}x = \frac{1}{3}$
解：
$\frac{1}{3}x = \frac{1}{3}$
$x = \frac{1}{3} ÷ \frac{1}{3}$
$x = 1$

3. 能简算的要简算。(12分)
$360÷15 - 2.5×1.4$ $\frac{5}{6}×\frac{2}{3}+\frac{4}{9}÷\frac{1}{6}$
$0.16 + 4÷(\frac{3}{8}-\frac{1}{8})$ $\frac{3}{7}-\frac{2}{5}+\frac{4}{7}-\frac{3}{5}$
$43×99 + 43$ $\frac{3}{5}÷[(\frac{1}{5}+\frac{1}{3})÷\frac{2}{9}]$

1. $360÷15 - 2.5×1.4$
$=24 - (2.5×1 + 2.5×0.4)$
$=24 - (2.5 + 1)$
$=24 - 3.5$
$=20.5$
2. $\frac{5}{6}×\frac{2}{3}+\frac{4}{9}÷\frac{1}{6}$
$=\frac{5}{9}+\frac{4}{9}×6$
$=\frac{5}{9}+\frac{24}{9}$
$=\frac{29}{9}$
3. $0.16 + 4÷(\frac{3}{8}-\frac{1}{8})$
$=0.16 + 4÷\frac{2}{8}$
$=0.16 + 4÷\frac{1}{4}$
$=0.16 + 16$
$=16.16$
4. $\frac{3}{7}-\frac{2}{5}+\frac{4}{7}-\frac{3}{5}$
$=(\frac{3}{7}+\frac{4}{7})-(\frac{2}{5}+\frac{3}{5})$
$=1 - 1$
$=0$
5. $43×99 + 43$
$=43×(99 + 1)$
$=43×100$
$=4300$
6. $\frac{3}{5}÷[(\frac{1}{5}+\frac{1}{3})÷\frac{2}{9}]$
$=\frac{3}{5}÷[(\frac{3}{15}+\frac{5}{15})×\frac{9}{2}]$
$=\frac{3}{5}÷[\frac{8}{15}×\frac{9}{2}]$
$=\frac{3}{5}÷\frac{12}{5}$
$=\frac{3}{5}×\frac{5}{12}$
$=\frac{1}{4}$