We have the following system of equations:
[tex]\begin{gathered} x+y=2, \\ 3x-4y=27. \end{gathered}[/tex]
We must eliminate x by summing the equations.
1) Before adding the equations, we multiply by -3 the first equation, we get:
[tex]\begin{gathered} -3x-3y=-6, \\ 3x-4y=27. \end{gathered}[/tex]
2) Now, summing the equations, we get:
[tex]\begin{gathered} (-3x-3y)+(3x-4y)=-6+27, \\ -7y=21. \end{gathered}[/tex]
Answer
-7y = 21
