Simple...
you have: 8x-6y=1
You're trying to find m-->>using y=mx+b to re-write the line....
8x-6y=1
8x-6y=1
-8x -8x
-6y=-8x+1
[tex] \frac{-6y}{-6} = \frac{-8x+1}{-6} [/tex]
y=[tex] \frac{4}{3} x- \frac{1}{6} [/tex]
Your slope m=[tex] \frac{4}{3} x[/tex]
Thus, your answer.