一、口算。
$\frac{1}{6} × 1.8 =$
$\frac{4}{7} + \frac{3}{4} =$
$\frac{1}{4} + \frac{4}{7} - \frac{4}{7} =$
$\frac{14}{15} ÷ \frac{7}{3} =$
$\frac{4}{5} + \frac{1}{3} =$
$\frac{7}{8} ÷ \frac{7}{5} × \frac{2}{5} =$
$\frac{8}{9} × \frac{2}{3} =$
$2 - \frac{1}{5} =$
$\frac{1}{5} × ( \frac{1}{2} + \frac{1}{3} ) =$
$81 ÷ \frac{9}{5} =$
$\frac{7}{8} ÷ \frac{7}{16} =$
$( \frac{7}{12} + \frac{3}{8} ) ÷ \frac{1}{48} =$
$\frac{2}{15} ÷ \frac{1}{6} =$
$\frac{5}{12} + \frac{2}{3} =$
$\frac{2}{5} ÷ \frac{6}{7} × \frac{3}{8} =$
$\frac{2}{3} - \frac{5}{9} =$
$\frac{7}{2} ÷ \frac{7}{6} =$
$\frac{3}{4} × 8 × \frac{1}{2} =$
$\frac{1}{4} × \frac{2}{7} =$
$\frac{14}{15} - \frac{2}{3} =$
$1 ÷ \frac{2}{5} × \frac{2}{5} =$

1.$\frac{3}{10}$ 2.$\frac{37}{28}$ 3.$\frac{1}{4}$ 4.$\frac{2}{5}$ 5.$\frac{17}{15}$ 6.$\frac{1}{4}$ 7.$\frac{16}{27}$ 8.$\frac{9}{5}$ 9.$\frac{1}{6}$ 10.45 11.2 12.46 13.$\frac{4}{5}$ 14.$\frac{13}{12}$ 15.$\frac{7}{40}$ 16.$\frac{1}{9}$ 17.3 18.3 19.$\frac{1}{14}$ 20.$\frac{4}{15}$ 21.1

二、计算下面各题，能用简便算法的就用简便算法。
$5×\frac{1}{5}÷5×\frac{1}{5}$
$(25+\frac{5}{8}+\frac{5}{12})÷5$
$(\frac{3}{4}+\frac{7}{8}-\frac{1}{16})×16$
$7÷25+\frac{7}{25}×99$
$(\frac{1}{2}-\frac{1}{4})÷\frac{1}{8}$
$(24×\frac{5}{6}-14)÷\frac{3}{13}$

1.$\frac{1}{25}$ 2.$5\frac{5}{24}$ 3.25 4.28 5.2 6.26