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![](https://rs.olm.vn/images/avt/0.png?1311)
Bài làm:
\(\frac{1,28}{3,15}=\frac{128}{315}\)
\(\frac{2}{5}:3\frac{1}{4}=\frac{8}{65}\)
\(\left(-1\frac{3}{7}\right):1,24=-\frac{250}{217}\)
\(2\frac{1}{\frac{5}{3\frac{1}{7}}}=\frac{92}{35}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{1,28}{3,15}=\frac{128}{315}\)
\(\frac{2}{5}:3\frac{1}{4}=\frac{2}{5}:\frac{13}{4}=\frac{2}{5}.\frac{4}{13}=\frac{8}{65}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\dfrac{1,28}{3,15}=\dfrac{128}{315}\)
b) \(\dfrac{2}{5}:3\dfrac{1}{4}=\dfrac{2}{5}:\dfrac{13}{4}=\dfrac{2}{5}\cdot\dfrac{4}{13}=\dfrac{8}{65}\)
c) \(\left(-1\dfrac{3}{7}\right):1,24=\dfrac{-10}{7}:\dfrac{31}{25}=\dfrac{-10}{7}\cdot\dfrac{25}{31}=\dfrac{-250}{217}\)
d) \(2\dfrac{1}{5}:3\dfrac{1}{7}=\dfrac{11}{5}:\dfrac{22}{7}=\dfrac{11}{5}\cdot\dfrac{7}{22}=\dfrac{7}{10}\)