Given, 7y=x.
Hence, substitute 7y for x in equation -x+3y=20.
[tex]\begin{gathered} -x+3y=20 \\ -7y+3y=20 \\ -4y=20 \\ y=-5 \end{gathered}[/tex]Now, substitute y=-5 in 7y=x.
[tex]\begin{gathered} 7\times(-5)=x \\ -35=x \end{gathered}[/tex]Therefore, the values of x and y are -35 and -5 respectively.
