一、口算。
$\frac{3}{8} × \frac{4}{5} =$
$\frac{5}{4} - \frac{3}{5} =$
$\frac{5}{6} × 2.4 =$
$\frac{9}{8} × \frac{4}{3} =$
$\frac{4}{25} × 50 =$
$\frac{9}{10} × \frac{5}{12} =$
$45 × \frac{3}{5} =$
$\frac{1}{8} + \frac{1}{9} =$
$1.1 × \frac{7}{22} =$
$1 - \frac{3}{8} =$
$\frac{5}{12} × 0.8 =$
$\frac{5}{12} + \frac{3}{4} =$
$\frac{2}{3} × \frac{6}{5} =$
$\frac{2}{5} × \frac{1}{4} =$
$1.8 × \frac{1}{6} =$
$\frac{4}{11} × \frac{11}{4} =$
$\frac{5}{6} × \frac{3}{4} =$
$\frac{3}{17} × \frac{2}{3} =$
$\frac{3}{5} × 0.4 =$
$\frac{4}{3} × \frac{27}{44} =$
$\frac{6}{11} × 2.2 =$

1.$\frac{3}{10}$ 2.$\frac{13}{20}$ 3.$2$ 4.$\frac{3}{2}$ 5.$8$ 6.$\frac{3}{8}$ 7.$27$ 8.$\frac{17}{72}$ 9.$\frac{7}{20}$ 10.$\frac{5}{8}$ 11.$\frac{1}{3}$ 12.$\frac{7}{6}$ 13.$\frac{4}{5}$ 14.$\frac{1}{10}$ 15.$\frac{3}{10}$ 16.$1$ 17.$\frac{5}{8}$ 18.$\frac{2}{17}$ 19.$\frac{6}{25}$ 20.$\frac{9}{11}$ 21.$\frac{6}{5}$

二、计算下面各题，能用简便算法的就用简便算法。
$\frac{8}{17}×7+\frac{8}{17}×10$
$\frac{3}{4}×\frac{5}{8}×\frac{4}{5}$
$1.5×(\frac{1}{3}+\frac{1}{5})$
$57×\frac{3}{28}$
$3.6×\frac{5}{8}×\frac{4}{15}$
$\frac{5}{6}-(\frac{3}{4}-\frac{3}{4}×\frac{2}{9})$

1.$8$ 2.$\frac{3}{8}$ 3.$0.8$ 4.$6\frac{3}{28}$ 5.$\frac{3}{5}$ 6.$\frac{1}{4}$