The ratio of present age of A and B is 2 : 3 . After 12 years the ratio of their ages will be 5 : 6 . What is B's present age ( in years ) ?

12

                       A      :     B

( given )           2      :     3

Present age of A = 2x     ,      Present age of B = 3X

After 12 years , age of A = 2x + 12   ,    age of B = 3x + 12

According to question , 

 \(\frac{2x\; +\; 12}{3x\;+\;12}\) = \(\frac{5}{6}\)

 12x + 72 = 15x + 60

 3x = 12

 x = 4

Present age of A = 2 × 4 = 8     ,    age of B = 3 × 4  = 12

B's age = 3 × 4 = 12 years