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第85页

信息发布者：

$\frac {1}{3}$

$\frac {1}{5}$

$\frac {9}{20}$

$\frac {1}{2}$

$\frac {33}{70}$

＞

＜

50.24

25.12

6.28

34.54

$=\frac {21}{24}-\frac {18}{24}+\frac {4}{24}$

$=\frac {1}{8}+\frac {4}{24}$

$=\frac {7}{24}$

$=\frac {5}{3}-(\frac {4}{9}+\frac {5}{9})$

$=\frac {5}{3}-1$

$=\frac {2}{3}$

$=\frac {45}{24}-(\frac {16}{24}-\frac {12}{24})$

$=\frac {45}{24}-\frac {1}{6}$

$=\frac {41}{24}$

$\begin{aligned}解：x&=15.2÷3.8\\x&=4\end{aligned}$

$\begin{aligned}解：x&=2×0.72\\x&=1.44\end{aligned}$

$\begin{aligned}解：2x&=0.64-0.36\\2x&=0.28\\x&=0.14\end{aligned}$

$\begin{aligned}解：0.7x&=12.6×2\\0.7x&=25.2\\x&=36\end{aligned}$

$\begin{aligned}解：1.2x&=0.3\\x&=0.25\end{aligned}$

$\begin{aligned}解：3x&=66+36\\3x&=102\\x&=34\end{aligned}$

$10÷2=5(\ \mathrm {cm})$

$10×5=50(\ \mathrm {cm}²)$

$3.14×5×5÷2=39.25(\ \mathrm {cm}²)$

$50-39.25=10.75(\ \mathrm {cm}²)$

$18÷2=9(\ \mathrm {cm})$

$18×9=162(\ \mathrm {cm}²)$

$3.14×9×9÷2=127.17(\ \mathrm {cm}²)$

$162-127.17=34.83(\ \mathrm {cm}²)$