We have the following system of equations:
[tex]\begin{gathered} x=-4\ldots(A) \\ 5x+4y=-16\ldots(B) \end{gathered}[/tex]Solving by substitution method.
If we substitute equation A into equation B, we get
[tex]5(-4)+4y=-16[/tex]since 5(-4)= -20, we have
[tex]-20+4y=-16[/tex]If we move -20 to the right hand side as +20, we obtain
[tex]\begin{gathered} 4y=-16+20 \\ \end{gathered}[/tex]since -16+20=20-16 = 4, we get
[tex]4y=4[/tex]and finally, y is equal to
[tex]\begin{gathered} y=\frac{4}{4} \\ y=1 \end{gathered}[/tex]Since equation A tells us that x=-4, the solution of the system is
[tex]\begin{gathered} x=-4 \\ y=1 \end{gathered}[/tex]