Giải:
\(38+5.\left(x-9\right)=123\)
\(\Leftrightarrow5.\left(x-9\right)=123-38\)
\(\Leftrightarrow5.\left(x-9\right)=85\)
\(\Leftrightarrow\left(x-9\right)=\dfrac{85}{5}\)
\(\Leftrightarrow x-9=17\)
\(\Leftrightarrow x=17+9\)
\(\Leftrightarrow x=26\)
Vậy \(x=26\).
Chúc bạn học tốt!
