一、口算。
$\frac{4}{5} ÷ 10\% =$
$1.03 - 30\% =$
$\frac{1}{7} + \frac{2}{3} =$
$\frac{5}{4} - \frac{4}{5} =$
$\frac{3}{10} ÷ 30\% =$
$4 × 20\% =$
$\frac{2}{5} × \frac{20}{3} =$
$72\% × \frac{5}{9} =$
$\frac{6}{19} ÷ \frac{3}{5} =$
$1\% ÷ 10\% =$
$\frac{6}{7} ÷ \frac{10}{13} =$
$\frac{1}{7} × \frac{7}{12} =$
$\frac{3}{4} ÷ \frac{5}{6} =$
$\frac{3}{4} ÷ \frac{7}{12} =$
$0.9 × \frac{2}{3} =$
$\frac{8}{5} - \frac{9}{10} =$
$6 × \frac{5}{12} =$
$\frac{3}{40} ÷ \frac{5}{2} =$
$\frac{29}{40} - \frac{2}{5} =$
$\frac{2}{15} ÷ 20\% =$
$\frac{2}{9} × \frac{9}{2} =$

1.$8$
2.$0.73$
3.$\frac{17}{21}$
4.$\frac{9}{20}$
5.$1$
6.$0.8$
7.$\frac{8}{3}$
8.$\frac{2}{5}$
9.$\frac{10}{19}$
10.$\frac{1}{10}$
11.$\frac{39}{35}$
12.$\frac{1}{12}$
13.$\frac{9}{10}$
14.$\frac{9}{7}$
15.$0.6$
16.$\frac{7}{10}$
17.$\frac{5}{2}$
18.$\frac{3}{100}$
19.$\frac{13}{40}$
20.$\frac{2}{3}$
21.$1$

二、计算下面各题，能用简便算法的就用简便算法。
$75\% × \frac{2}{3} ÷ 2$
$100 - 98.6 × 40\%$
$75\% × [ (1 - \frac{2}{5}) × 25\% ]$
$8 × \frac{7}{9} × 12.5\% × \frac{3}{7}$
$( \frac{3}{4} - 10\% ÷ 2 ) × \frac{5}{14}$
$2.5 × \frac{4}{5} + 80\% × 6.5 + 0.8$

1.$\frac{1}{4}$
2.$60.56$
3.$\frac{9}{80}$
4.$\frac{1}{3}$
5.$\frac{1}{4}$
6.$8$