We have the following equation given:
[tex]4x=7y-z[/tex]We need to solve for y when x=8 and 7z=-4. If we solve for y we got:
[tex]7y=4x+z[/tex]And dividing both sides by 7 we got:
[tex]y=\frac{4x+z}{7}[/tex]We can use the condition 7z=-4 in order to solve for z and we got:
[tex]z=-\frac{4}{7}[/tex]Now we can replace x and z in order to solve for y and we got:
[tex]y=\frac{4(8)+(-\frac{4}{7})}{7}=\frac{32-(\frac{4}{7})}{7}=\frac{220}{49}[/tex]