Answer:
Option 2 - 20 unit
Explanation:
Given : If ED = 10 and DB = 3x -8
To find : What is the length of EB ?
Solution :
According to the figure,
ED is equal to DB with similar sign.
So, ED=DB
Substitute the values,



Put back,

unit
Now, length of EB=ED+DB

unit
Therefore, option 2 is correct.