2. 把下列分数约分，约分结果是假分数的化成整数或带分数。
$\dfrac{4}{6}$
$\dfrac{38}{95}$
$\dfrac{39}{91}$
$\dfrac{12}{27}$
$\dfrac{12}{8}$
$\dfrac{35}{14}$
$\dfrac{48}{32}$
$\dfrac{24}{8}$

$\dfrac{4}{6}=\dfrac{4÷2}{6÷2}=\dfrac{2}{3}$
$\dfrac{38}{95}=\dfrac{38÷19}{95÷19}=\dfrac{2}{5}$
$\dfrac{39}{91}=\dfrac{39÷13}{91÷13}=\dfrac{3}{7}$
$\dfrac{12}{27}=\dfrac{12÷3}{27÷3}=\dfrac{4}{9}$
$\dfrac{12}{8}=\dfrac{12÷4}{8÷4}=\dfrac{3}{2}=1\dfrac{1}{2}$
$\dfrac{35}{14}=\dfrac{35÷7}{14÷7}=\dfrac{5}{2}=2\dfrac{1}{2}$
$\dfrac{48}{32}=\dfrac{48÷16}{32÷16}=\dfrac{3}{2}=1\dfrac{1}{2}$
$\dfrac{24}{8}=\dfrac{24÷8}{8÷8}=3$

3. 先化简，再比一比。（在“$◯$”里填“$＞$”“$＜$”或“$=$”。）
$\dfrac{15}{35}◯\dfrac{3}{7}$
$\dfrac{6}{15}◯\dfrac{3}{5}$
$\dfrac{3}{21}◯\dfrac{1}{8}$
$\dfrac{8}{16}◯\dfrac{18}{36}$
$\dfrac{49}{21}◯\dfrac{39}{9}$
$\dfrac{22}{77}◯\dfrac{27}{63}$

$\dfrac{15}{35}=\dfrac{15÷5}{35÷5}=\dfrac{3}{7}$
$\dfrac{15}{35}=\dfrac{3}{7}$
$\dfrac{6}{15}=\dfrac{6÷3}{15÷3}=\dfrac{2}{5}$
$\dfrac{2}{5}＜\dfrac{3}{5}$，$\dfrac{6}{15}＜\dfrac{3}{5}$
$\dfrac{3}{21}=\dfrac{3÷3}{21÷3}=\dfrac{1}{7}$
$\dfrac{1}{7}＞\dfrac{1}{8}$，$\dfrac{3}{21}＞\dfrac{1}{8}$
$\dfrac{8}{16}=\dfrac{8÷8}{16÷8}=\dfrac{1}{2}$
$\dfrac{18}{36}=\dfrac{18÷18}{36÷18}=\dfrac{1}{2}$
$\dfrac{8}{16}=\dfrac{18}{36}$
$\dfrac{49}{21}=\dfrac{49÷7}{21÷7}=\dfrac{7}{3}$
$\dfrac{39}{9}=\dfrac{39÷3}{9÷3}=\dfrac{13}{3}$
$\dfrac{7}{3}＜\dfrac{13}{3}$，$\dfrac{49}{21}＜\dfrac{39}{9}$
$\dfrac{22}{77}=\dfrac{22÷11}{77÷11}=\dfrac{2}{7}$
$\dfrac{27}{63}=\dfrac{27÷9}{63÷9}=\dfrac{3}{7}$
$\dfrac{2}{7}＜\dfrac{3}{7}$，$\dfrac{22}{77}＜\dfrac{27}{63}$

4. 在括号里填最简分数。
1250 克 = () 千克
150 厘米 = () 米
100 分 = () 时
8 个月 = () 年
230 平方分米 = () 平方米
20 时 = () 日
105 千克 = () 吨
300 米 = () 千米
65 公顷 = () 平方千米

1250÷1000 = $\frac{1250}{1000}$ = $\frac{5}{4}$
1250克 = ($\frac{5}{4}$)千克
150÷100 = $\frac{150}{100}$ = $\frac{3}{2}$
150厘米 = ($\frac{3}{2}$)米
100÷60 = $\frac{100}{60}$ = $\frac{5}{3}$
100分 = ($\frac{5}{3}$)时
8÷12 = $\frac{8}{12}$ = $\frac{2}{3}$
8个月 = ($\frac{2}{3}$)年
230÷100 = $\frac{230}{100}$ = $\frac{23}{10}$
230平方分米 = ($\frac{23}{10}$)平方米
20÷24 = $\frac{20}{24}$ = $\frac{5}{6}$
20时 = ($\frac{5}{6}$)日
105÷1000 = $\frac{105}{1000}$ = $\frac{21}{200}$
105千克 = ($\frac{21}{200}$)吨
300÷1000 = $\frac{300}{1000}$ = $\frac{3}{10}$
300米 = ($\frac{3}{10}$)千米
65÷100 = $\frac{65}{100}$ = $\frac{13}{20}$
65公顷 = ($\frac{13}{20}$)平方千米

5. 算一算。
$\dfrac{7}{9}+\dfrac{2}{9}=$
$\dfrac{11}{12}-\dfrac{7}{12}=$
$\dfrac{13}{20}+\dfrac{3}{20}=$
$\dfrac{16}{25}+\dfrac{24}{25}=$
$\dfrac{19}{30}-\dfrac{7}{30}=$
$\dfrac{7}{24}+\dfrac{23}{24}=$
$\dfrac{4}{15}+\dfrac{8}{15}=$
$\dfrac{7}{16}-\dfrac{1}{16}=$

$\dfrac{7}{9}+\dfrac{2}{9}=\dfrac{7+2}{9}=\dfrac{9}{9}=1$
$\dfrac{11}{12}-\dfrac{7}{12}=\dfrac{11-7}{12}=\dfrac{4}{12}=\dfrac{1}{3}$
$\dfrac{13}{20}+\dfrac{3}{20}=\dfrac{13+3}{20}=\dfrac{16}{20}=\dfrac{4}{5}$
$\dfrac{16}{25}+\dfrac{24}{25}=\dfrac{16+24}{25}=\dfrac{40}{25}=\dfrac{8}{5}$
$\dfrac{19}{30}-\dfrac{7}{30}=\dfrac{19-7}{30}=\dfrac{12}{30}=\dfrac{2}{5}$
$\dfrac{7}{24}+\dfrac{23}{24}=\dfrac{7+23}{24}=\dfrac{30}{24}=\dfrac{5}{4}$
$\dfrac{4}{15}+\dfrac{8}{15}=\dfrac{4+8}{15}=\dfrac{12}{15}=\dfrac{4}{5}$
$\dfrac{7}{16}-\dfrac{1}{16}=\dfrac{7-1}{16}=\dfrac{6}{16}=\dfrac{3}{8}$

6. 解方程。
$x+\dfrac{5}{12}=\dfrac{11}{12}$
$\dfrac{29}{30}-x=\dfrac{7}{30}$
$\dfrac{3}{11}+x=\dfrac{9}{11}$
$x-\dfrac{7}{10}=\dfrac{3}{10}$

解：$x+\dfrac{5}{12}=\dfrac{11}{12}$
$x=\dfrac{11}{12}-\dfrac{5}{12}$
$x=\dfrac{6}{12}$
$x=\dfrac{1}{2}$
解：$\dfrac{29}{30}-x=\dfrac{7}{30}$
$x=\dfrac{29}{30}-\dfrac{7}{30}$
$x=\dfrac{22}{30}$
$x=\dfrac{11}{15}$
解：$\dfrac{3}{11}+x=\dfrac{9}{11}$
$x=\dfrac{9}{11}-\dfrac{3}{11}$
$x=\dfrac{6}{11}$
解：$x-\dfrac{7}{10}=\dfrac{3}{10}$
$x=\dfrac{3}{10}+\dfrac{7}{10}$
$x=\dfrac{10}{10}$
$x=1$