一、口算。
$\frac{11}{12} - \frac{4}{9} =$
$\frac{13}{45} × \frac{9}{39} =$
$\frac{5}{8} ÷ \frac{3}{4} =$
$1.1 - 99\% =$
$\frac{6}{7} × \frac{7}{6} =$
$12.5\% × 8 =$
$25\% ÷ \frac{4}{5} =$
$\frac{5}{13} ÷ \frac{20}{39} =$
$\frac{2}{27} ÷ \frac{4}{9} =$
$7.1 + 9\% =$
$2.6 × \frac{5}{13} =$
$1 - \frac{5}{7} =$
$\frac{5}{51} × \frac{17}{15} =$
$\frac{1}{2} + \frac{3}{5} =$
$\frac{3}{4} ÷ \frac{3}{4} ÷ \frac{4}{3} =$
$13 - \frac{3}{4} ÷ \frac{1}{4} =$
$\frac{5}{4} + \frac{4}{5} × 125\% =$
$\frac{2}{3} ÷ \frac{4}{5} + \frac{7}{6} =$
$(1 - \frac{7}{8}) ÷ \frac{7}{8} =$
$68\% + 7.3 + 0.32 =$
$\frac{3}{4} ÷ \frac{1}{6} + \frac{1}{2} =$

1.$\frac{17}{36}$ 2.$\frac{1}{15}$ 3.$\frac{3}{4}$ 4.$0.11$ 5.$1$ 6.$2$ 7.$1$ 8.$\frac{2}{7}$ 9.$\frac{1}{7}$ 10.$1$ 11.$\frac{1}{9}$ 12.$8.3$ 13.$\frac{5}{16}$ 14.$1.1$ 15.$5$ 16.$\frac{3}{4}$ 17.$\frac{3}{4}$ 18.$10$ 19.$\frac{5}{6}$ 20.$7.19$ 21.$2\frac{1}{4}$

二、计算下面各题，能用简便算法的就用简便算法。
$\frac{4}{7} × \frac{15}{22} × \frac{7}{12}$
$\frac{4}{5} ÷ ( \frac{5}{6} × \frac{3}{5} ) - 50\%$
$( \frac{1}{3} + \frac{4}{15} × \frac{5}{6} ) ÷ \frac{20}{21}$
$( \frac{4}{5} + \frac{1}{4} ) ÷ \frac{7}{3} + \frac{7}{10}$
$\frac{1}{4} × \frac{4}{5} + 90\% ÷ 45\%$
$80\% ÷ [ ( \frac{3}{5} + \frac{1}{2} ) × 2 ]$

1.$\frac{5}{22}$ 2.$\frac{11}{10}$ 3.$\frac{7}{12}$ 4.$\frac{23}{20}$ 5.$2\frac{1}{5}$ 6.$\frac{4}{11}$