Theo đề, ta có hệ phương trình:
\(\left\{{}\begin{matrix}4a+3b=156000\\5a+7b=234000\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}20a+15b=780000\\20a+28b=936000\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}b=12000\\a=30000\end{matrix}\right.\)