the first step is replacing x=8 on the first equation, so
[tex]4(8)+y=6[/tex]the second step is do the multiplication
[tex]\begin{gathered} 32+y=6 \\ y+32=6 \end{gathered}[/tex]and the last step is place the 32 on the other side substracting
[tex]\begin{gathered} y=6-32 \\ y=-26 \end{gathered}[/tex]