\(\Leftrightarrow x+\dfrac{4}{5}=9-\dfrac{3}{7}-\dfrac{3}{5}=\dfrac{279}{35}\)
hay x=251/35
\(x+\dfrac{4}{5}=\dfrac{45}{5}-\left(\dfrac{3}{7}+\dfrac{3}{5}\right)\)
<=>\(x=\dfrac{45}{5}-\dfrac{3}{7}-\dfrac{3}{5}-\dfrac{4}{5}=\dfrac{38}{5}-\dfrac{3}{7}=\dfrac{266}{35}-\dfrac{15}{35}=\dfrac{251}{35}\)