how do I find the following answer to parts B?

Since the triangle is divided in half, we can asume the following relationship:
[tex]5x-4=2\cdot(2x+1)[/tex]Solving for x we get the following:
[tex]\begin{gathered} 5x-4=2\cdot(2x+1) \\ \Rightarrow5x-4=4x+2 \\ \Rightarrow5x-4x=2+4 \\ \Rightarrow x=6 \end{gathered}[/tex]therefore, x=6