電子課本網 › 第43頁

第43頁

信息發(fā)布者：

1

6

$\frac{5}{4}$

$3\frac{1}{3}$（或$\frac{10}{3}$）

$\frac{7}{4}$

2

$\frac{12}{35}$

$\frac{1}{16}$

 $(\frac{2}{5}+\frac{5}{9})\times45$

 $=\frac{2}{5}\times45+\frac{5}{9}\times45$

 $=18 + 25$

 $=43$

$5-(\frac{6}{7}\div\frac{3}{14}+\frac{3}{16})$

 $=5-(4+\frac{3}{16})$

 $=5 - 4-\frac{3}{16}$

 $=1-\frac{3}{16}$

 $=\frac{13}{16}$

$\frac{1}{4}\div(\frac{2}{3}+\frac{1}{2})\times\frac{4}{5}$

 $=\frac{1}{4}\div(\frac{4}{6}+\frac{3}{6})\times\frac{4}{5}$

 $=\frac{1}{4}\div\frac{7}{6}\times\frac{4}{5}$

 $=\frac{1}{4}\times\frac{6}{7}\times\frac{4}{5}$

 $=\frac{6}{35}$

$\frac{8}{9}\times\frac{2}{5}+\frac{3}{5}\div\frac{9}{8}$

$=\frac{8}{9}\times\frac{2}{5}+\frac{3}{5}\times\frac{8}{9}$

$=\frac{8}{9}\times(\frac{2}{5}+\frac{3}{5})$

$=\frac{8}{9}\times1$

$=\frac{8}{9}$

$(\frac{24}{19}+\frac{16}{17})\times\frac{1}{8}+\frac{15}{17}$

 $=\frac{24}{19}\times\frac{1}{8}+\frac{16}{17}\times\frac{1}{8}+\frac{15}{17}$

 $=\frac{3}{19}+\frac{2}{17}+\frac{15}{17}$

 $=\frac{3}{19}+(\frac{2}{17}+\frac{15}{17})$

 $=\frac{3}{19}+1$

 $=1\frac{3}{19}$（或$\frac{22}{19}$）

$\frac{2}{25}\div[\frac{8}{9}\times(\frac{1}{2}-\frac{1}{5})]$

 $=\frac{2}{25}\div[\frac{8}{9}\times(\frac{5}{10}-\frac{2}{10})]$

 $=\frac{2}{25}\div(\frac{8}{9}\times\frac{3}{10})$

 $=\frac{2}{25}\div\frac{4}{15}$

 $=\frac{2}{25}\times\frac{15}{4}$

 $=\frac{3}{10}$

 解：$x + 20\%x = 360$

 $1.2x = 360$

 $x = 360\div1.2$

 $x = 300$

 解：$7x-\frac{2}{3}=\frac{2}{3}$

 $7x=\frac{2}{3}+\frac{2}{3}$

 $7x=\frac{4}{3}$

 $x=\frac{4}{3}\div7$

 $x=\frac{4}{21}$

 解：$\frac{5}{7}x\div\frac{5}{14}=\frac{7}{8}$

 $\frac{5}{7}x=\frac{7}{8}\times\frac{5}{14}$

 $\frac{5}{7}x=\frac{5}{16}$

 $x=\frac{5}{16}\div\frac{5}{7}$

 $x=\frac{7}{16}$

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4

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25

二五

0.25

120

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45

5

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