三、在□里填上合适的数。（最后一行每空2分，其余每空1分，共16分）
$\frac{8}{5}$ $\xrightarrow{× 3}$ $□$ $\xrightarrow{× \frac{1}{4}}$ $□$ $\xrightarrow{× \frac{5}{6}}$ $□$ $\xrightarrow{× 3\frac{2}{9}}$ $□$
$\frac{3}{8}$ $\xrightarrow{× \frac{5}{2}}$ $□$ $\xrightarrow{÷ \frac{3}{4}}$ $\xrightarrow{÷ \frac{7}{4}}$ $□$ $\xrightarrow{× \frac{14}{3}}$ $□$
$□$ $\xrightarrow{÷ \frac{7}{18}}$ $□$ $\xrightarrow{× \frac{7}{10}}$ $□$ $\xrightarrow{÷ \frac{9}{5}}$ $□$ $\xrightarrow{× \frac{5}{4}}$ $\frac{5}{12}$

1.$\frac{24}{5}$ 2.$\frac{6}{5}$ 3.1 4.$3\frac{2}{9}$ 5.$\frac{15}{16}$ 6.$\frac{5}{4}$ 7.$\frac{5}{7}$ 8.$\frac{10}{3}$ 9.$\frac{1}{3}$ 10.$\frac{6}{7}$ 11.$\frac{3}{5}$ 12.$\frac{1}{3}$

四、计算下面各题，能用简便算法的就用简便算法。（每题4分，共48分）
$\frac{2}{9}×\frac{5}{8}÷\frac{5}{6}$
$\frac{25}{9}÷\frac{3}{4}÷\frac{4}{3}$
$\frac{5}{8}×\frac{5}{7}+\frac{3}{8}÷\frac{7}{5}$
$\frac{2}{9}+\frac{1}{2}÷\frac{4}{5}+\frac{3}{8}$
$3-\frac{3}{5}×\frac{5}{21}-\frac{6}{7}$
$(15+\frac{5}{2})÷\frac{5}{2}-\frac{1}{4}$
$(1-\frac{1}{4}-\frac{5}{12})÷\frac{2}{3}$
$21÷(\frac{1}{3}+\frac{2}{5})×\frac{11}{9}$
$[\frac{3}{5}-(\frac{9}{16}-\frac{2}{5})]×\frac{8}{9}$
$4÷(\frac{1}{3}-\frac{1}{5})÷\frac{1}{2}$
$75×\frac{75}{76}-\frac{1}{76}$
$18×\frac{3}{4}+23÷\frac{4}{3}-\frac{3}{4}$

1.$\frac{1}{6}$ 2.$\frac{25}{9}$ 3.$\frac{5}{7}$ 4.$1\frac{2}{9}$ 5.2 6.$6\frac{3}{4}$ 7.$\frac{1}{2}$ 8.35 9.$\frac{7}{18}$ 10.60 11.74 12.30