Câu trả lời:
\(x+x\times\dfrac{1}{4}:\dfrac{2}{7}+x:\dfrac{2}{9}=255\)
\(x+x\times\dfrac{7}{8}+x\times\dfrac{9}{2}=255\)
\(x+\left(1+\dfrac{7}{8}+\dfrac{9}{2}\right)=255\)
\(x\times\dfrac{51}{8}=255\)
\(x=255:\dfrac{51}{8}\left(255\times\dfrac{8}{51}\right)\)
\(x=40\)
tk cho mk nhé