\(\Leftrightarrow\dfrac{5}{2}-x+\dfrac{4}{5}=\dfrac{26}{21}\\ \Leftrightarrow\dfrac{33}{10}-x=\dfrac{26}{21}\\ \Leftrightarrow x=\dfrac{33}{10}-\dfrac{26}{21}=\dfrac{433}{210}\)
Ta có: \(\dfrac{3}{2}-x+\dfrac{4}{5}=\dfrac{2}{3}-\left(-\dfrac{4}{7}\right)\)
\(\Leftrightarrow\dfrac{23}{10}-x=\dfrac{2}{3}+\dfrac{4}{7}=\dfrac{26}{21}\)
hay \(x=\dfrac{223}{210}\)
\(2\dfrac{1}{2}-x+\dfrac{4}{5}=\dfrac{2}{3}-\dfrac{-4}{7}\)
<=> \(2-x+\dfrac{4}{5}=\dfrac{2}{3}+\dfrac{4}{7}\)
<=> \(2+\dfrac{4}{5}-\dfrac{2}{3}-\dfrac{4}{7}=x\)
<=> x = \(\dfrac{164}{105}\)
