In 10 years, A will be twice as old as B was 10 years ago. If A is now 9 years older than B, the present age of B is:
19 years
29 years
39 years
49 years
Explanation:
Let the present ages of B and A be x years and (x+9) years respectively.
Then 10 years ago Bs age is (x - 10) and in the next 10 years As age is (x + 19)
Given that As age is twice of B
So (x + 19) = 2 x (x - 10) ⇒⇒ x + 19 = 2x - 20 ⇒⇒ x = 39
Let the present ages of B and A be x years and (x+9) years respectively.
Then 10 years ago Bs age is (x - 10) and in the next 10 years As age is (x + 19)
Given that As age is twice of B
So (x + 19) = 2 x (x - 10) ⇒⇒ x + 19 = 2x - 20 ⇒⇒ x = 39