Question

10 years later a will be twice as old as B and 5 years ago he was 3 times as old as b what are the present ages a and b

Answer 1

Let the ages of A and B be x and y years respectively.

Then, according to the conditions given in the question:-

x + 10 = 2(y + 10)x - 10 = 12 (y - 10)

On solving these two equations simultaneously, we get the answers to be x=34 and y=12.

Thus the age of A is 34 years and that of B is 12 years.

Hope this helps :)

Answer 2

Let A and B the 2 present ages.
Ten years later, A is twice as old as B
(A + 10) = 2(B + 10) (1)
Five years ago, A was 3 times as old as B
(A - 5) = 3(B - 5) (2). 
From (2) A = 3B - 15 + 5 = 3B - 10.
Replace this value of A into (1)
3B - 10 + 10 = 2B + 20 --> B = 20. Then, 
A = 3B - 10 = 60 - 10 = 50.
So age of a is 50
Age of b is 20