help................

Answer: DB is 5
Step-by-step explanation:
Alright, lets get started.
Since given that AD is parallel to CB.
And AB is parallel to CD.
And the angle A is given as 90°
It means the given figure is a rectangle.
And the diagonals of the rectangle are equal to each other.
So, [tex]DB=AC[/tex]
So, [tex]DB=5[/tex]
Hence the answer is 5 ... Answer
Hope it will help :)