[tex]\huge\mathfrak\blue{answer}[/tex]
[tex] = q - \frac{q91}{2} = \frac{k}{9} [/tex]
[tex]\blue{switch \: sides}[/tex]
[tex] = \frac{k}{9} = q - \frac{q91}{2} [/tex]
[tex]\blue{multiply \: 9 \: both \: sides}[/tex]
[tex] = \frac{9k}{9} = 9q - 9 \: . \: \frac{q91}{2} [/tex]
[tex]\blue{lastly \: simplify}[/tex]
[tex] =\underline {k = 9q - \frac{{9q}^{91} }{2} }[/tex]
(mark me brainliest if you're satisfied)