1. 直接写出得数。
$ \frac{17}{18} - \frac{5}{18} = $$ $$ \frac{17}{28} - \frac{3}{28} = $$ $$ \frac{7}{15} + \frac{8}{15} = $$ $$ \frac{39}{50} + \frac{13}{50} - \frac{27}{50} = $
$ \frac{2}{5} + \frac{1}{5} = $$ $$ \frac{2}{21} + \frac{9}{21} = $$ $$ \frac{9}{17} - \frac{2}{17} = $$ $$ \frac{26}{39} - \frac{17}{39} - \frac{5}{39} = $
$ \frac{5}{16} - \frac{3}{16} = $$ $$ \frac{19}{45} - \frac{5}{45} = $$ $$ \frac{3}{13} + \frac{7}{13} = $$ $$ \frac{7}{11} + \frac{5}{11} - \frac{4}{11} = $
$ 2.6 × 8 = $$ $$ 2.36 - 1.47 = $$ $$ 9.2 × 5 = $$ $$ 0.09 ÷ 0.3 + 7 = $
$ 18.4 ÷ 0.2 = $$ $$ 300 × 1.4 = $$ $$ 9.5 ÷ 25 = $$ $$ 4.2 × 0.4 × 5 = $
$ 42.3 - 3.2 = $$ $$ 8.8 + 1.6 = $$ $$ 6 - 1.7 = $$ $$ 1200 × 0.01 ÷ 5 = $
$ 14.4 ÷ 12 = $$ $$ 10 - 7.4 = $$ $$ 3.3 ÷ 30 = $$ $$ 3.3 × 99 + 3.3 = $

1. $\dfrac{12}{18}$ $\dfrac{14}{28}$ $1$ $\dfrac{25}{50}$
$\dfrac{3}{5}$ $\dfrac{11}{21}$ $\dfrac{7}{17}$ $\dfrac{4}{39}$
$\dfrac{2}{16}$ $\dfrac{14}{45}$ $\dfrac{10}{13}$ $\dfrac{8}{11}$
$20.8$ $0.89$ $46$ $7.3$
$92$ $420$ $0.38$ $8.4$
$39.1$ $10.4$ $4.3$ $2.4$
$1.2$ $2.6$ $0.11$ $330$

2. 解方程。
$ 2.6x + x = 4.32 $$ $$ 6x - 4.8 × 0.4 = 5.28 $$ $$ x ÷ (2.3 + 0.7) = 15.6 $
$ 1.5x + 9.6 = 17.1 $$ $$ 8(x - 0.9) = 5.36 $$ $$ 28.4 + 4.6 - 5x = 2.4 $

2. $x=1.2$ $x=1.2$ $x=46.8$
$x=5$ $x=1.57$ $x=6.12$

已知$ \frac{A}{B} $是一个真分数，且$ A + B = 23 ，$$ \frac{A + 5}{B - 2} $是假分数，则$ \frac{A}{B} $可能是多少$？$　　

思维提升
$\dfrac{A}{B}$可能是$\dfrac{8}{15}$、$\dfrac{9}{14}$、$\dfrac{10}{13}$、$\dfrac{11}{12}$。