一、口算。
$\frac{10}{9} ÷ \frac{2}{3} =$
$8.8 × 50\% =$
$\frac{7}{10} × \frac{8}{21} ÷ \frac{4}{5} =$
$\frac{7}{20} × \frac{10}{21} =$
$\frac{6}{7} - \frac{1}{2} =$
$\frac{1}{100} ÷ \frac{1}{25} × \frac{1}{4} =$
$\frac{2}{7} ÷ \frac{8}{7} =$
$\frac{9}{8} × \frac{4}{7} =$
$( \frac{2}{5} - \frac{1}{3} ) × 15 =$
$0.1 ÷ 2\% =$
$\frac{1}{2} ÷ \frac{7}{8} =$
$6 ÷ \frac{6}{7} × \frac{7}{6} =$
$\frac{7}{15} + \frac{1}{5} =$
$16 × 75\% =$
$30 × (45\% - 0.3) =$
$\frac{4}{5} × \frac{7}{10} =$
$81 ÷ \frac{9}{5} =$
$\frac{12}{19} + 4 × \frac{7}{38} =$
$\frac{8}{25} ÷ \frac{4}{15} =$
$\frac{10}{27} - \frac{5}{18} =$
$( \frac{3}{4} - \frac{1}{3} ) × 24 =$

1.$\frac{5}{3}$ 2.$4.4$ 3.$\frac{1}{3}$ 4.$\frac{1}{6}$ 5.$\frac{5}{14}$ 6.$\frac{1}{16}$ 7.$\frac{1}{4}$ 8.$\frac{9}{14}$ 9.$1$ 10.$5$ 11.$\frac{4}{7}$ 12.$\frac{49}{6}$ 13.$\frac{2}{3}$ 14.$12$ 15.$4.5$ 16.$\frac{14}{25}$ 17.$45$ 18.$\frac{26}{19}$ 19.$\frac{6}{5}$ 20.$\frac{5}{54}$ 21.$10$

二、计算下面各图形中涂色部分的面积。
1.
2.

1. $1+2+3=6(\mathrm{m})$
$3.14×(6÷2)^2-3.14×(1÷2)^2-3.14×(2÷2)^2-3.14×(3÷2)^2=17.27(\mathrm{m}^2)$
2. $12×6=72(\mathrm{cm}^2)$