一、口算。
$\frac{9}{4} ÷ \frac{45}{8} =$
$\frac{1}{8} + \frac{5}{7} =$
$( \frac{2}{87} - \frac{1}{58} ) ÷ \frac{1}{29} =$
$\frac{5}{14} ÷ \frac{5}{8} =$
$\frac{4}{5} × \frac{1}{3} =$
$\frac{4}{9} × \frac{1}{5} ÷ \frac{4}{5} =$
$\frac{15}{16} × \frac{8}{9} =$
$\frac{2}{5} ÷ \frac{4}{11} =$
$83 × \frac{1}{83} - \frac{4}{5} =$
$\frac{3}{4} ÷ \frac{2}{5} =$
$\frac{5}{8} - \frac{1}{2} =$
$25 - 36 × \frac{2}{9} =$
$0.8 × \frac{5}{8} =$
$\frac{17}{18} × \frac{9}{11} =$
$\frac{3}{4} ÷ \frac{9}{10} × \frac{3}{5} =$
$25 ÷ \frac{5}{6} =$
$\frac{5}{8} - \frac{1}{3} =$
$\frac{1}{5} × \frac{1}{8} ÷ \frac{1}{10} =$
$\frac{3}{4} × \frac{4}{5} =$
$\frac{1}{12} + \frac{4}{15} =$
$\frac{1}{7} × \frac{7}{9} × 54 =$

1.$\frac{2}{5}$ 2.$\frac{47}{56}$ 3.$\frac{1}{6}$ 4.$\frac{4}{7}$ 5.$\frac{4}{15}$ 6.$\frac{1}{9}$ 7.$\frac{5}{6}$ 8.$\frac{11}{10}$ 9.$\frac{1}{5}$ 10.$\frac{15}{8}$ 11.$\frac{1}{8}$ 12.17 13.$\frac{1}{2}$ 14.$\frac{17}{22}$ 15.$\frac{1}{2}$ 16.30 17.$\frac{7}{24}$ 18.$\frac{1}{4}$ 19.$\frac{3}{5}$ 20.$\frac{7}{20}$ 21.6

二、计算下面各题，能用简便算法的就用简便算法。
$\frac{3}{5} ÷ ( \frac{5}{12} + \frac{5}{8} × \frac{2}{15} )$
$( \frac{2}{3} + \frac{7}{9} × \frac{9}{28} ) ÷ \frac{11}{12}$
$2 × 5 × 7 × ( \frac{1}{2} + \frac{1}{5} + \frac{1}{7} )$
$( \frac{4}{9} + \frac{2}{15} ) ÷ \frac{2}{15}$
$\frac{4}{7} × \frac{4}{9} + \frac{5}{9} ÷ \frac{7}{4}$
$( \frac{6}{13} + \frac{1}{21} ) × 13 + \frac{8}{21}$

1.$\frac{6}{5}$ 2.1 3.59 4.$\frac{13}{3}$ 5.$\frac{4}{7}$ 6.7