PLEAASE HELPPP whoever solves this will mark brainliest

Answer:
12
Step-by-step explanation:
Perimeter of ΔABC = 12+ perimeter of ΔACD
Perimeter of ΔABC= AC+CB+BA
Perimeter of ΔACD=AC+CD+DA
But, CB=CD +DB
DA ≅DB since there is a ⊥bisector trough D and
Therefore,
Perimeter of ΔABC= (AC+CD+DA)+BA = Perimeter of ΔACD +12 therefore AB=12