In a certain kindergarten, every child has got either a dog or a cat or both. 18 children have got dogs only and 6 children have got both dogs and cats. If there are 30 children in the kindergarten, how many of them have cats?
Options.
A) 6  B) 12  C) 14  D) 16  E) 20

Rationale: a : only cats b : both cats and dogs c : only dogs as per question , a + b + c = 30 c = 18 b = 6 , so a = 6 . hence , a + b = 12 . answer is b
Answer: B