A is two years older than B who is twice as old as C. If the total of the ages of A, B and C be 27, then how old is B?

Let C's age be x years. Then, B's age = 2x years. A's age = (2x + 2) years.

 (2x + 2) + 2x + x = 27

 5x = 25

 x = 5.

Hence, B's age = 2x = 10 years.