Answer:
8
Explanation:
To solve for ED, create proportion between the two similar triangles.

where Big represents the bigger triangle an little represents the smaller triangle.

Cross multiply and solve for x.
9(x+4)=6(2x+4)
9x+36=12x+24
9x+36-24=12x+24-24
9x+12=12x
9x-9x+12=12x-9x
12=3x
4=x
Lastly substitute the value into ED which is x+4.
4+4=8