Answer:
[tex] - 3f + 1 = - 5 \\ - 3f = - 5 - 1 \\ - 3f = - 6 \\ \\ f = \frac{ - 6}{ - 3} \\ \\ f = \frac{6}{3} \\ \\ f = 2[/tex]
I hope I helped you^_^
