Since both triangles are aproximately equal, we can say that:
[tex]\begin{gathered} ED=AB \\ \rightarrow4y+2=6y-4 \end{gathered}[/tex]Solving for y :
[tex]\begin{gathered} 4y+2=6y-4 \\ \rightarrow2+4=6y-4y \\ \rightarrow8=2y\rightarrow\frac{8}{2}=y \\ \\ \Rightarrow y=4 \end{gathered}[/tex]Substituting in the expression for AB,
[tex]\begin{gathered} AB=6y-4 \\ \rightarrow AB=6(4)-4 \\ \rightarrow AB=20 \end{gathered}[/tex]Thereby, AB = 20