Answer:
The length of segment AB is 5.5 mm.
Explanation:
As segment BD is parallel to segment AE (as indicated by the arrows on the line segments), use the the Side Splitter Theorem for similar triangles to determine the length of segment AB.
Similar Triangles - Side Splitter Theorem
If a line parallel to one side of a triangle intersects the other two sides, then this line divides those two sides proportionally.
Therefore, according to the Side Splitter Theorem:






Therefore, the length of segment AB is 5.5 mm.