HELLO...!!!
[tex]\begin{cases}&y=2x+4\\&3x+y=9\end{cases}[/tex]
[tex]\underline{\textbf{Add\ "y"\ in\ Eq.\ 2:}}\\ \\3x+2x+4=9\\ \\5x+4=9\\ \\5x=9-4\\ \\5x=5\\ \\x= \dfrac{5}{5}\\ \\x=1\quad\checkmark\\ \\ \\\underline{\textbf{Add\ "x"\ in\ Eq.\ 1:}}\\ \\y=2(1)+4\\ \\y=2+4\\ \\y=6\quad\checkmark\\ \\ \\\mathbb{ANSWER:}\Longrightarrow\boxed{\boxed{\boldsymbol{x=1\ ;\ y=6}}}\\ \\ \\\textbf{HOPE\ THIS\ HELPS...!!}[/tex]