[tex]\begin{cases}x+y=150\smallskip\\\dfrac{x}{y}=\dfrac{4}{1}\end{cases}\Leftrightarrow\begin{cases}x+y=150\smallskip\\x=4y\end{cases}\Leftrightarrow\begin{cases}5y=150\smallskip\\x=4y\end{cases}\Leftrightarrow\begin{cases}y=30\smallskip\\x=120\end{cases}[/tex]
[tex]150=120+30[/tex]
