一、口算。
$\frac{5}{12} ÷ \frac{7}{4} =$
$\frac{5}{6} ÷ \frac{2}{9} =$
$\frac{5}{14} ÷ \frac{10}{21} =$
$\frac{3}{8} × 24 =$
$\frac{1}{2} + \frac{3}{10} =$
$6 ÷ \frac{3}{5} =$
$\frac{5}{4} - \frac{5}{8} =$
$\frac{5}{6} ÷ \frac{3}{2} =$
$21 ÷ \frac{7}{11} =$
$\frac{3}{7} ÷ 6 =$
$\frac{4}{5} × \frac{5}{4} =$
$\frac{5}{8} ÷ \frac{5}{6} =$
$\frac{4}{5} ÷ \frac{8}{9} =$
$\frac{3}{10} × \frac{5}{9} =$
$\frac{1}{3} - \frac{1}{7} =$
$\frac{5}{14} ÷ \frac{5}{14} =$
$\frac{1}{3} ÷ \frac{1}{99} =$
$\frac{1}{8} ÷ \frac{5}{2} =$
$\frac{13}{14} ÷ \frac{16}{35} =$
$\frac{6}{7} ÷ \frac{48}{49} =$
$\frac{1}{4} + \frac{5}{8} =$

1.$\frac{5}{21}$ 2.$\frac{15}{4}$ 3.$\frac{3}{4}$ 4.$9$ 5.$\frac{4}{5}$ 6.$10$ 7.$\frac{5}{8}$ 8.$\frac{5}{9}$ 9.$33$ 10.$\frac{1}{14}$ 11.$1$ 12.$\frac{3}{4}$ 13.$\frac{9}{10}$ 14.$\frac{1}{6}$ 15.$\frac{4}{21}$ 16.$1$ 17.$33$ 18.$\frac{1}{20}$ 19.$\frac{65}{32}$ 20.$\frac{7}{8}$ 21.$\frac{7}{8}$

二、计算下面各题，能用简便算法的就用简便算法。
$\frac{11}{12} ÷ \frac{2}{3} ÷ \frac{11}{14}$
$\frac{2}{3} - (\frac{1}{6} + \frac{1}{4}) ÷ \frac{3}{4}$
$\frac{7}{18} × \frac{1}{4} + \frac{3}{4} ÷ \frac{18}{7}$
$\frac{9}{26} ÷ \frac{6}{13} + 0.25$
$(\frac{1}{2} + \frac{3}{4} + \frac{5}{6}) ÷ \frac{1}{24}$
$\frac{4}{5} ÷ [ (\frac{7}{8} - 0.75) ÷ \frac{5}{8} ]$

1.$\frac{7}{4}$ 2.$\frac{1}{9}$ 3.$\frac{7}{18}$ 4.$1$ 5.$50$ 6.$4$