Giải:
a) \(\left(\dfrac{9}{25}-2.18\right):\left(\dfrac{19}{5}+0,2\right)\)
\(=\left(-\dfrac{891}{25}\right):4\)
\(=-\dfrac{891}{100}\)
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b) \(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)
\(=1+\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)
\(=\left(1+0,5\right)+\left(\dfrac{4}{23}-\dfrac{4}{23}\right)+\left(\dfrac{5}{21}+\dfrac{16}{21}\right)\)
\(=1,5+0+1\)
\(=2,5\)
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