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第56页

信息发布者：

$=\frac {8}{24}+\frac {9}{24}$

$=\frac {17}{24}$

$=\frac {5}{5}-\frac {2}{5}$

$=\frac {3}{5}$

$=\frac {9}{15}-\frac {7}{15}$

$=\frac {2}{15}$

$=\frac {7}{14}-\frac {6}{14}$

$=\frac {1}{14}$

$=\frac {54}{63}-\frac {35}{63}$

$=\frac {19}{63}$

$=\frac {49}{28}+\frac {4}{28}$

$=\frac {53}{28}$

$\begin{aligned}解：x&=\frac {5}{9}+\frac {2}{3}\\x&=\frac {11}{9}\end{aligned}$

$\begin{aligned}解：x&=\frac {4}{5}-\frac {5}{8}\\x&=\frac {7}{40}\end{aligned}$

$\begin{aligned}解：x&=1-\frac {3}{7}\\x&= \frac {4}{7}\end{aligned}$

$\frac{8}{15}$

$\frac{13}{40}$

$\frac{14}{45}$

$\frac{2}{15}$

$\frac{3}{40}$

$\frac{4}{45}$

分子为1的两个分数相加减,其结果

的分母为两个分母相乘,分子为两

个分母相加减。

$250$克$= \frac {1}{4}$千克

$600$克$= \frac {3}{5}$千克

$ \frac {3}{5}+ \frac {1}{4}= \frac {17}{20}($千克)

$\frac {3}{5}- \frac {1}{4}= \frac {7}{20}($千克)

答：两种饼干的质量一共是$ \frac {17}{20}$千克，大盒饼干比小包饼干多$ \frac {7}{20}$千克.

$\frac {17}{20}+\frac {3}{5}+\frac {17}{20}=\frac {23}{10}($吨)

答：这批货物一共有$\frac {23}{10}$吨.

$\frac {7}{8}-\frac {1}{2}+\frac {3}{4}$

$=\frac {7}{8}-\frac {4}{8}+\frac {6}{8}$

$=\frac {9}{8}$

答：运来香蕉$\frac {9}{8}$吨.

$1-\frac {3} {8}×2$

$=1-\frac {3} {4}$

$=\frac {1} {4} ({米} )$

答：它的底边长是$\frac {1} {4}$米.