1. 直接写出得数。
$0.5-\frac{1}{8}$ $\frac{3}{4}÷\frac{3}{8}$ $\frac{3}{7}÷\frac{1}{2}$ $\frac{3}{4}×\frac{2}{3}$

1. $\frac{3}{8}$ 2 $\frac{6}{7}$ $\frac{1}{2}$

2. 一个长方体,长是$\frac{3}{4}$米,宽是$\frac{1}{2}$米,体积是$\frac{5}{8}$立方米,长方体的高是多少？

$\frac{5}{8}÷\frac{1}{2}÷\frac{3}{4}=\frac{5}{3}$(米)

$\frac{5}{8} ÷ \frac{3}{4} ÷ \frac{1}{2} = \frac{5}{3}$(米)

3. 计算下面各题。
$\frac{8}{9}÷\frac{5}{6}×\frac{3}{16}-\frac{1}{8}$ $\frac{5}{4}-\frac{9}{14}÷\frac{6}{5}+\frac{2}{3}$ $0.25÷\frac{5}{8}+\frac{2}{3}÷\frac{5}{8}$
$\frac{3}{4}÷\frac{6}{7}÷\frac{14}{3}-\frac{1}{32}$ $5÷[(\frac{1}{4}+\frac{1}{8})×12]$ $\frac{3}{8}÷[0.7-(1-\frac{1}{2})]$

3. $\frac{3}{40}$ $\frac{29}{21}$ $\frac{22}{15}$ $\frac{5}{32}$ $\frac{10}{9}$ $\frac{15}{8}$

$\frac{8}{9}÷\frac{5}{6}×\frac{3}{16}-\frac{1}{8}$
$=\frac{8}{9}×\frac{6}{5}×\frac{3}{16}-\frac{1}{8}$
$=\frac{16}{15}×\frac{3}{16}-\frac{1}{8}$
$=\frac{1}{5}-\frac{1}{8}$
$=\frac{3}{40}$
$\frac{5}{4}-\frac{9}{14}÷\frac{6}{5}+\frac{2}{3}$
$=\frac{5}{4}-\frac{9}{14}×\frac{5}{6}+\frac{2}{3}$
$=\frac{5}{4}-\frac{15}{28}+\frac{2}{3}$
$=\frac{35}{28}-\frac{15}{28}+\frac{2}{3}$
$=\frac{20}{28}+\frac{2}{3}$
$=\frac{5}{7}+\frac{2}{3}$
$=\frac{15}{21}+\frac{14}{21}$
$=\frac{29}{21}$
$0.25÷\frac{5}{8}+\frac{2}{3}÷\frac{5}{8}$
$=\frac{1}{4}×\frac{8}{5}+\frac{2}{3}×\frac{8}{5}$
$=(\frac{1}{4}+\frac{2}{3})×\frac{8}{5}$
$=(\frac{3}{12}+\frac{8}{12})×\frac{8}{5}$
$=\frac{11}{12}×\frac{8}{5}$
$=\frac{22}{15}$
$\frac{3}{4}÷\frac{6}{7}÷\frac{14}{3}-\frac{1}{32}$
$=\frac{3}{4}×\frac{7}{6}×\frac{3}{14}-\frac{1}{32}$
$=\frac{7}{8}×\frac{3}{14}-\frac{1}{32}$
$=\frac{3}{16}-\frac{1}{32}$
$=\frac{6}{32}-\frac{1}{32}$
$=\frac{5}{32}$
$5÷[(\frac{1}{4}+\frac{1}{8})×12]$
$=5÷[(\frac{2}{8}+\frac{1}{8})×12]$
$=5÷(\frac{3}{8}×12)$
$=5÷\frac{9}{2}$
$=5×\frac{2}{9}$
$=\frac{10}{9}$
$\frac{3}{8}÷[0.7-(1-\frac{1}{2})]$
$=\frac{3}{8}÷[0.7 - 0.5]$
$=\frac{3}{8}÷0.2$
$=\frac{3}{8}÷\frac{1}{5}$
$=\frac{3}{8}×5$
$=\frac{15}{8}$

4. 某食堂运来28吨面粉,已经吃了15天,平均每天吃$\frac{2}{5}$吨；余下的面粉每天吃$\frac{2}{7}$吨,还可以吃多少天？

$(28-\frac{2}{5}×15)÷\frac{2}{7}=77$(天)