The line is:
[tex]-3x-4y=1[/tex]Which is equivalent to:
[tex]\begin{gathered} \Rightarrow4y=-3x-1 \\ \Rightarrow y=-\frac{3x}{4}-\frac{1}{4} \end{gathered}[/tex]Thus, the slope of the line is equal to -3/4
a) Every line parallel to that one has the same slope, then the answer is -3/4
b) On the other hand, if m_1 and m_2 are the slopes of two perpendicular lines, then:
[tex]m_1\cdot m_2=-1[/tex]Therefore, since the slope of our line is equal to -3/4, the slope of any line perpendicular to that one is:
[tex]\begin{gathered} m_1\cdot(-\frac{3}{4})=-1 \\ \Rightarrow m_1=\frac{4}{3} \end{gathered}[/tex]Hence, the answer is 4/3
