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一、解方程。
$\frac {1}{7}+x= \frac {5}{12}$
$8x-\frac {1}{3}= \frac {1}{9}$
$\frac {5}{7}x×\frac {3}{5}= \frac {10}{21}$
$x×\frac {2}{5}= 20×\frac {3}{4}$
$(1+\frac {2}{11})x= \frac {52}{3}$
$\frac {2}{3}x÷\frac {1}{3}= 14$
$\frac {1}{7}+x= \frac {5}{12}$
$8x-\frac {1}{3}= \frac {1}{9}$
$\frac {5}{7}x×\frac {3}{5}= \frac {10}{21}$
$x×\frac {2}{5}= 20×\frac {3}{4}$
$(1+\frac {2}{11})x= \frac {52}{3}$
$\frac {2}{3}x÷\frac {1}{3}= 14$
答案
三、$\frac{64}{81}$ 3 $\frac{33}{155}$ $18\frac{2}{3}$ $\frac{1}{24}$ $\frac{4}{9}$ $\frac{35}{32}$ 29 $1\frac{7}{8}$ 21 $\frac{3}{2}$ 4 6 $\frac{19}{20}$ $\frac{99}{25}$
解析
解：
1. $\frac{1}{7} + x = \frac{5}{12}$
$x = \frac{5}{12} - \frac{1}{7}$
$x = \frac{35}{84} - \frac{12}{84} = \frac{23}{84}$
2. $8x - \frac{1}{3} = \frac{1}{9}$
$8x = \frac{1}{9} + \frac{1}{3} = \frac{1}{9} + \frac{3}{9} = \frac{4}{9}$
$x = \frac{4}{9} ÷ 8 = \frac{4}{9} × \frac{1}{8} = \frac{1}{18}$
3. $\frac{5}{7}x × \frac{3}{5} = \frac{10}{21}$
$\frac{3}{7}x = \frac{10}{21}$
$x = \frac{10}{21} ÷ \frac{3}{7} = \frac{10}{21} × \frac{7}{3} = \frac{10}{9}$
4. $x × \frac{2}{5} = 20 × \frac{3}{4}$
$\frac{2}{5}x = 15$
$x = 15 ÷ \frac{2}{5} = 15 × \frac{5}{2} = \frac{75}{2}$
5. $(1 + \frac{2}{11})x = \frac{52}{3}$
$\frac{13}{11}x = \frac{52}{3}$
$x = \frac{52}{3} ÷ \frac{13}{11} = \frac{52}{3} × \frac{11}{13} = \frac{44}{3}$
6. $\frac{2}{3}x ÷ \frac{1}{3} = 14$
$\frac{2}{3}x × 3 = 14$
$2x = 14$
$x = 7$
1. $\frac{1}{7} + x = \frac{5}{12}$
$x = \frac{5}{12} - \frac{1}{7}$
$x = \frac{35}{84} - \frac{12}{84} = \frac{23}{84}$
2. $8x - \frac{1}{3} = \frac{1}{9}$
$8x = \frac{1}{9} + \frac{1}{3} = \frac{1}{9} + \frac{3}{9} = \frac{4}{9}$
$x = \frac{4}{9} ÷ 8 = \frac{4}{9} × \frac{1}{8} = \frac{1}{18}$
3. $\frac{5}{7}x × \frac{3}{5} = \frac{10}{21}$
$\frac{3}{7}x = \frac{10}{21}$
$x = \frac{10}{21} ÷ \frac{3}{7} = \frac{10}{21} × \frac{7}{3} = \frac{10}{9}$
4. $x × \frac{2}{5} = 20 × \frac{3}{4}$
$\frac{2}{5}x = 15$
$x = 15 ÷ \frac{2}{5} = 15 × \frac{5}{2} = \frac{75}{2}$
5. $(1 + \frac{2}{11})x = \frac{52}{3}$
$\frac{13}{11}x = \frac{52}{3}$
$x = \frac{52}{3} ÷ \frac{13}{11} = \frac{52}{3} × \frac{11}{13} = \frac{44}{3}$
6. $\frac{2}{3}x ÷ \frac{1}{3} = 14$
$\frac{2}{3}x × 3 = 14$
$2x = 14$
$x = 7$
二、简便计算下面各题。
$\frac {2}{5}×\frac {4}{3}+\frac {1}{5}÷\frac {3}{4}$
$\frac {1}{4}+\frac {3}{4}×\frac {1}{3}+\frac {3}{4}$
$48×(\frac {1}{16}+\frac {1}{12})$
$\frac {7}{16}÷\frac {1}{45}+\frac {9}{16}×45$
$(\frac {1}{4}+\frac {1}{5})×4×5$
$\frac {5}{7}+\frac {5}{9}÷\frac {8}{9}+\frac {3}{8}$
$\frac {17}{19}×18+\frac {17}{19}×2-\frac {17}{19}$
$99×\frac {97}{98}$
$27÷26+27×\frac {25}{26}$
$\frac {2}{5}×\frac {4}{3}+\frac {1}{5}÷\frac {3}{4}$
$\frac {1}{4}+\frac {3}{4}×\frac {1}{3}+\frac {3}{4}$
$48×(\frac {1}{16}+\frac {1}{12})$
$\frac {7}{16}÷\frac {1}{45}+\frac {9}{16}×45$
$(\frac {1}{4}+\frac {1}{5})×4×5$
$\frac {5}{7}+\frac {5}{9}÷\frac {8}{9}+\frac {3}{8}$
$\frac {17}{19}×18+\frac {17}{19}×2-\frac {17}{19}$
$99×\frac {97}{98}$
$27÷26+27×\frac {25}{26}$
答案
$\frac{2}{5}×\frac{4}{3}+\frac{1}{5}÷\frac{3}{4}$
$=\frac{2}{5}×\frac{4}{3}+\frac{1}{5}×\frac{4}{3}$
$=(\frac{2}{5}+\frac{1}{5})×\frac{4}{3}$
$=\frac{3}{5}×\frac{4}{3}$
$=\frac{4}{5}$
$\frac{1}{4}+\frac{3}{4}×\frac{1}{3}+\frac{3}{4}$
$=\frac{1}{4}+\frac{1}{4}+\frac{3}{4}$
$=(\frac{1}{4}+\frac{1}{4})+\frac{3}{4}$
$=\frac{2}{4}+\frac{3}{4}$
$=\frac{5}{4}$
$48×(\frac{1}{16}+\frac{1}{12})$
$=48×\frac{1}{16}+48×\frac{1}{12}$
$=3 + 4$
$=7$
$\frac{7}{16}÷\frac{1}{45}+\frac{9}{16}×45$
$=\frac{7}{16}×45+\frac{9}{16}×45$
$=(\frac{7}{16}+\frac{9}{16})×45$
$=1×45$
$=45$
$(\frac{1}{4}+\frac{1}{5})×4×5$
$=\frac{1}{4}×4×5+\frac{1}{5}×4×5$
$=5 + 4$
$=9$
$\frac{5}{7}+\frac{5}{9}÷\frac{8}{9}+\frac{3}{8}$
$=\frac{5}{7}+\frac{5}{9}×\frac{9}{8}+\frac{3}{8}$
$=\frac{5}{7}+\frac{5}{8}+\frac{3}{8}$
$=\frac{5}{7}+(\frac{5}{8}+\frac{3}{8})$
$=\frac{5}{7}+1$
$=1\frac{5}{7}$
$\frac{17}{19}×18+\frac{17}{19}×2-\frac{17}{19}$
$=\frac{17}{19}×(18 + 2 - 1)$
$=\frac{17}{19}×19$
$=17$
$99×\frac{97}{98}$
$=(98 + 1)×\frac{97}{98}$
$=98×\frac{97}{98}+1×\frac{97}{98}$
$=97+\frac{97}{98}$
$=97\frac{97}{98}$
$27÷26+27×\frac{25}{26}$
$=27×\frac{1}{26}+27×\frac{25}{26}$
$=27×(\frac{1}{26}+\frac{25}{26})$
$=27×1$
$=27$
$=\frac{2}{5}×\frac{4}{3}+\frac{1}{5}×\frac{4}{3}$
$=(\frac{2}{5}+\frac{1}{5})×\frac{4}{3}$
$=\frac{3}{5}×\frac{4}{3}$
$=\frac{4}{5}$
$\frac{1}{4}+\frac{3}{4}×\frac{1}{3}+\frac{3}{4}$
$=\frac{1}{4}+\frac{1}{4}+\frac{3}{4}$
$=(\frac{1}{4}+\frac{1}{4})+\frac{3}{4}$
$=\frac{2}{4}+\frac{3}{4}$
$=\frac{5}{4}$
$48×(\frac{1}{16}+\frac{1}{12})$
$=48×\frac{1}{16}+48×\frac{1}{12}$
$=3 + 4$
$=7$
$\frac{7}{16}÷\frac{1}{45}+\frac{9}{16}×45$
$=\frac{7}{16}×45+\frac{9}{16}×45$
$=(\frac{7}{16}+\frac{9}{16})×45$
$=1×45$
$=45$
$(\frac{1}{4}+\frac{1}{5})×4×5$
$=\frac{1}{4}×4×5+\frac{1}{5}×4×5$
$=5 + 4$
$=9$
$\frac{5}{7}+\frac{5}{9}÷\frac{8}{9}+\frac{3}{8}$
$=\frac{5}{7}+\frac{5}{9}×\frac{9}{8}+\frac{3}{8}$
$=\frac{5}{7}+\frac{5}{8}+\frac{3}{8}$
$=\frac{5}{7}+(\frac{5}{8}+\frac{3}{8})$
$=\frac{5}{7}+1$
$=1\frac{5}{7}$
$\frac{17}{19}×18+\frac{17}{19}×2-\frac{17}{19}$
$=\frac{17}{19}×(18 + 2 - 1)$
$=\frac{17}{19}×19$
$=17$
$99×\frac{97}{98}$
$=(98 + 1)×\frac{97}{98}$
$=98×\frac{97}{98}+1×\frac{97}{98}$
$=97+\frac{97}{98}$
$=97\frac{97}{98}$
$27÷26+27×\frac{25}{26}$
$=27×\frac{1}{26}+27×\frac{25}{26}$
$=27×(\frac{1}{26}+\frac{25}{26})$
$=27×1$
$=27$
