一、口算。
$\frac{15}{4} ÷ \frac{3}{2} =$
$0.9 × \frac{5}{18} =$
$1 - \frac{7}{12} + \frac{5}{12} =$
$\frac{3}{2} - \frac{4}{3} =$
$\frac{1}{8} × \frac{2}{5} =$
$20 × \frac{3}{4} + 20 =$
$\frac{1}{25} ÷ \frac{1}{10} =$
$\frac{2}{3} - \frac{4}{9} =$
$( \frac{7}{16} - \frac{1}{4} ) × 8 =$
$\frac{5}{3} × \frac{8}{3} =$
$\frac{4}{3} × \frac{9}{20} =$
$\frac{3}{8} ÷ \frac{3}{10} × \frac{1}{3} =$
$\frac{8}{9} + \frac{1}{3} =$
$\frac{6}{7} ÷ \frac{4}{7} =$
$121 × \frac{7}{11} - 70 =$
$\frac{1}{12} ÷ \frac{4}{15} =$
$\frac{2}{3} + \frac{2}{5} =$
$14 ÷ ( \frac{4}{5} - \frac{9}{20} ) =$
$\frac{4}{5} + \frac{1}{8} =$
$\frac{11}{6} ÷ \frac{22}{3} =$
$\frac{6}{7} × 2 ÷ \frac{6}{7} × 2 =$

1.$\frac{5}{2}$ 2.$\frac{1}{4}$ 3.$\frac{5}{6}$ 4.$\frac{1}{6}$ 5.$\frac{1}{20}$ 6.35 7.$\frac{2}{5}$ 8.$\frac{2}{9}$ 9.$\frac{3}{2}$ 10.$\frac{40}{9}$ 11.$\frac{3}{5}$ 12.$\frac{5}{12}$ 13.$\frac{11}{9}$ 14.$\frac{3}{2}$ 15.7 16.$\frac{5}{16}$ 17.$\frac{16}{15}$ 18.40 19.$\frac{37}{40}$ 20.$\frac{1}{4}$ 21.4

二、计算下面各题，能用简便算法的就用简便算法。
$24×\frac{16}{7}×\frac{7}{8}$
$(\frac{5}{6}+\frac{5}{8})×2.4$
$\frac{14}{31}×23+\frac{17}{31}×23-23$
$(\frac{7}{12}-\frac{1}{8})÷\frac{1}{12}×\frac{2}{5}$
$8÷\frac{4}{5}-\frac{4}{5}÷8$
$\frac{3}{5}÷(\frac{4}{5}+\frac{5}{8}×\frac{2}{15})$

1.48 2.3.5 3.0 4.$\frac{11}{5}$ 5.$9\frac{9}{10}$ 6.$\frac{36}{53}$