Answer:
[tex]f(x) = - 8 \\ \\ - 7x - 1 = - 8 \\ \\ - 7x = - 8 + 1 \\ \\ - 7x = - 7 \\ \\ 7x = 7 \\ \\ x = \frac{7}{7} \\ \\ x = 1[/tex]