Given the system of equations
[tex]\begin{cases}x+y=-3 \\ 3x+4y=-7\end{cases}[/tex]
Solve by elimination method as shown below.
Multiply the first equation by 3 and subtract it from the second equation,
[tex]\begin{gathered} 3(x+y)=3(-3) \\ \Rightarrow3x+3y=-9 \end{gathered}[/tex]
Then,
[tex]\begin{gathered} \Rightarrow(3x+4y)-(3x+3y)=-7-(-9) \\ \Rightarrow y=-7+9=2 \\ \Rightarrow y=2 \end{gathered}[/tex]
Use the value of y in the first equation,
[tex]\begin{gathered} y=2 \\ \Rightarrow x+2=-3 \\ \Rightarrow x=-5 \end{gathered}[/tex]
Therefore, the answers are x=-5 and y=2, (x,y)=(-5,2)
