1. 直接写出得数。
$ \frac{5}{12} × \frac{4}{3} = $$ $$ \frac{7}{9} × \frac{1}{4} = $$ $$ \frac{21}{48} × \frac{33}{14} = $$ $$ \frac{4}{27} × \frac{3}{8} = $
$ \frac{3}{4} × \frac{1}{6} = $$ $$ \frac{1}{3} × \frac{2}{5} = $$ $$ \frac{11}{12} × \frac{6}{11} = $$ $$ \frac{5}{21} × \frac{7}{10} = $
$ \frac{2}{3} × \frac{2}{3} = $$ $$ \frac{4}{5} × \frac{5}{8} = $$ $$ \frac{5}{9} × \frac{6}{25} = $$ $$ \frac{37}{42} × \frac{21}{74} = $
$ \frac{7}{10} × \frac{1}{2} = $$ $$ \frac{2}{15} × \frac{10}{7} = $$ $$ \frac{5}{6} × \frac{2}{3} = $$ $$ \frac{16}{9} × \frac{3}{4} = $
$ \frac{5}{6} × \frac{9}{10} = $$ $$ \frac{2}{11} × \frac{5}{8} = $$ $$ \frac{11}{14} × \frac{7}{55} = $$ $$ \frac{18}{19} × \frac{19}{18} = $
$ \frac{7}{24} × \frac{3}{28} = $$ $$ \frac{2}{7} × \frac{5}{3} = $$ $$ \frac{9}{10} × \frac{5}{18} = $$ $$ \frac{14}{9} × \frac{7}{18} = $

1. $\frac{5}{9}$ $\frac{7}{36}$ $\frac{33}{32}$ $\frac{1}{18}$
$\frac{1}{8}$ $\frac{2}{15}$ $\frac{1}{2}$ $\frac{1}{6}$
$\frac{4}{9}$ $\frac{1}{2}$ $\frac{2}{15}$ $\frac{1}{4}$
$\frac{7}{20}$ $\frac{4}{21}$ $\frac{5}{9}$ $\frac{4}{3}$
$\frac{3}{4}$ $\frac{5}{44}$ $\frac{1}{10}$ 1
$\frac{1}{32}$ $\frac{10}{21}$ $\frac{1}{4}$ $\frac{49}{81}$

2. 解方程。
$ 8x - 2.6 = 3 $$ $$ 4.2x ÷ 7 = 5.52 $$ $$ 0.3(x + 1.4) = 27 $
$ 2.2x + 4.6 = 5.04 $$ $$ x - 0.9x = 0.8 $$ $$ 6.2 ÷ 4 + 5x = 7.2 $

2. $x = 0.7$ $x = 9.2$ $x = 88.6$
$x = 0.2$ $x = 8$ $x = 1.13$

对于非零的任意数 $ a $、$ b(a ≠ b) $，都有 $ a * b = \frac{a + b}{b - a} × \frac{b}{a} $，那么 $ 3 * 5 $ 的值是()。

思维提升
$\frac{20}{3}$