Let us say that:
 x = age of brad
 x + 2 = age of Alexandra
 (x + 2) – 3 = age of Cecilia = x – 1
  
 We are also given that:
 x + x + 2 + x – 1 = 37
 
 solving for x:
 3x + 1 = 37
 3x = 36
 x = 12 = age of brad
 x + 2 = 14 = age of Alexandra
 x – 1 = 11 = age of cecilia