三、计算下面各题,怎样简便就怎样计算。
$\frac {8}{9}×\frac {8}{9}÷\frac {8}{9}×\frac {8}{9}$
$\frac {3}{4}÷(1-\frac {1}{2}-\frac {1}{4})$
$\frac {22}{31}×\frac {5}{4}÷(\frac {14}{3}-\frac {1}{2})$
$10÷\frac {5}{9}+\frac {1}{9}×6$
$\frac {1}{16}+\frac {1}{2}×\frac {5}{8}-\frac {1}{3}$
$(\frac {1}{2}+\frac {1}{3})÷\frac {3}{5}-\frac {17}{18}$
$\frac {7}{8}×(\frac {7}{2}-\frac {3}{2}÷\frac {2}{3})$
$(\frac {7}{9}-\frac {3}{8})×72$
$\frac {7}{8}+\frac {3}{4}×\frac {16}{15}+\frac {1}{5}$
$(30+\frac {5}{7})×\frac {7}{10}-\frac {1}{2}$
$[1-(\frac {1}{4}+\frac {3}{8})]÷\frac {1}{4}$
$\frac {4}{5}÷[(\frac {5}{8}-\frac {1}{2})÷\frac {5}{8}]$
$21-21÷\frac {7}{2}-21÷\frac {7}{3}$
$\frac {7}{8}×\frac {2}{5}+\frac {2}{5}+\frac {1}{5}$
$\frac {99}{100}÷\frac {1}{2}÷\frac {2}{3}÷\frac {3}{4}$

$\frac{8}{9}×\frac{8}{9}÷\frac{8}{9}×\frac{8}{9}$
$=\frac{8}{9}×\frac{8}{9}×\frac{9}{8}×\frac{8}{9}$
$=(\frac{8}{9}×\frac{9}{8})×(\frac{8}{9}×\frac{8}{9})$
$=1×\frac{64}{81}$
$=\frac{64}{81}$
$\frac{3}{4}÷(1 - \frac{1}{2} - \frac{1}{4})$
$=\frac{3}{4}÷(\frac{1}{2} - \frac{1}{4})$
$=\frac{3}{4}÷\frac{1}{4}$
$=\frac{3}{4}×4$
$=3$
$\frac{22}{31}×\frac{5}{4}÷(\frac{14}{3} - \frac{1}{2})$
$=\frac{22}{31}×\frac{5}{4}÷(\frac{28}{6} - \frac{3}{6})$
$=\frac{22}{31}×\frac{5}{4}÷\frac{25}{6}$
$=\frac{22}{31}×\frac{5}{4}×\frac{6}{25}$
$=\frac{22}{31}×\frac{3}{10}$
$=\frac{33}{155}$
$10÷\frac{5}{9}+\frac{1}{9}×6$
$=10×\frac{9}{5}+\frac{2}{3}$
$=18 + \frac{2}{3}$
$=18\frac{2}{3}$
$\frac{1}{16}+\frac{1}{2}×\frac{5}{8}-\frac{1}{3}$
$=\frac{1}{16}+\frac{5}{16}-\frac{1}{3}$
$=\frac{6}{16}-\frac{1}{3}$
$=\frac{3}{8}-\frac{1}{3}$
$=\frac{9}{24}-\frac{8}{24}$
$=\frac{1}{24}$
$(\frac{1}{2}+\frac{1}{3})÷\frac{3}{5}-\frac{17}{18}$
$=(\frac{3}{6}+\frac{2}{6})×\frac{5}{3}-\frac{17}{18}$
$=\frac{5}{6}×\frac{5}{3}-\frac{17}{18}$
$=\frac{25}{18}-\frac{17}{18}$
$=\frac{8}{18}$
$=\frac{4}{9}$
$\frac{7}{8}×(\frac{7}{2}-\frac{3}{2}÷\frac{2}{3})$
$=\frac{7}{8}×(\frac{7}{2}-\frac{3}{2}×\frac{3}{2})$
$=\frac{7}{8}×(\frac{7}{2}-\frac{9}{4})$
$=\frac{7}{8}×(\frac{14}{4}-\frac{9}{4})$
$=\frac{7}{8}×\frac{5}{4}$
$=\frac{35}{32}$
$(\frac{7}{9}-\frac{3}{8})×72$
$=\frac{7}{9}×72 - \frac{3}{8}×72$
$=56 - 27$
$=29$
$\frac{7}{8}+\frac{3}{4}×\frac{16}{15}+\frac{1}{5}$
$=\frac{7}{8}+\frac{4}{5}+\frac{1}{5}$
$=\frac{7}{8}+(\frac{4}{5}+\frac{1}{5})$
$=\frac{7}{8}+1$
$=1\frac{7}{8}$
$(30 + \frac{5}{7})×\frac{7}{10}-\frac{1}{2}$
$=30×\frac{7}{10}+\frac{5}{7}×\frac{7}{10}-\frac{1}{2}$
$=21 + \frac{1}{2}-\frac{1}{2}$
$=21$
$[1 - (\frac{1}{4}+\frac{3}{8})]÷\frac{1}{4}$
$=[1 - (\frac{2}{8}+\frac{3}{8})]×4$
$=(1 - \frac{5}{8})×4$
$=\frac{3}{8}×4$
$=\frac{3}{2}$
$\frac{4}{5}÷[(\frac{5}{8}-\frac{1}{2})÷\frac{5}{8}]$
$=\frac{4}{5}÷[(\frac{5}{8}-\frac{4}{8})×\frac{8}{5}]$
$=\frac{4}{5}÷(\frac{1}{8}×\frac{8}{5})$
$=\frac{4}{5}÷\frac{1}{5}$
$=\frac{4}{5}×5$
$=4$
$21 - 21÷\frac{7}{2}-21÷\frac{7}{3}$
$=21 - 21×\frac{2}{7}-21×\frac{3}{7}$
$=21 - 6 - 9$
$=6$
$\frac{7}{8}×\frac{2}{5}+\frac{2}{5}+\frac{1}{5}$
$=\frac{7}{20}+\frac{8}{20}+\frac{4}{20}$
$=\frac{19}{20}$
$\frac{99}{100}÷\frac{1}{2}÷\frac{2}{3}÷\frac{3}{4}$
$=\frac{99}{100}×2×\frac{3}{2}×\frac{4}{3}$
$=\frac{99}{100}×4$
$=\frac{99}{25}$