Answer:
B
Step-by-step explanation:
let y = f(x) and rearrange making x the subject, that is
y = 9x + 7 ( subtract 7 from both sides )
y - 7 = 9x ( divide all terms by 9 )
[tex]\frac{1}{9}[/tex] y - [tex]\frac{7}{9}[/tex] = x
Change y back into terms of x with x = [tex]f^{-1}[/tex](x) , thus
[tex]f^{-1}[/tex] (x) = [tex]\frac{1}{9}[/tex] x - [tex]\frac{7}{9}[/tex] → B
