Since M is the midpoint of line CB, then line CM has equal length as line MB. We have;
[tex]3x+1=5x-9[/tex]
Then, we collect like terms;
[tex]\begin{gathered} 1+9=5x-3x \\ 2x=10 \end{gathered}[/tex]
Divide both sides of the equation by 2;
[tex]\begin{gathered} \frac{2x}{2}=\frac{10}{2} \\ x=5 \end{gathered}[/tex]
CORRECT OPTION: 5
