Question

In $10$ years, $A$ will be twice as old as $B$ was $10$ years ago. If at present $A$ is $9$ years older than $B$, the present age of $B$ is

• A. $19$ years
• B. $29$ years
• C. $39$ years
• D. $49$ years

Answer 1

Answer: (C)

$39$ years

Let the present age of B be $x$ years. ,
Then, the present age of A would be $(x+9)$ years.
After 10 years, the age of A would be $(x+9+10)=(x+19)$ years and before then years, the age of B was $(x-10)$ years.

Now, from the information given in the question,
$(x+19)=2(x-10)$
or $x+19=2x-20$ or $x=19+20=39$ years
Therefore, the present age of B is $39$ years.

Hence, the correct answer is (C).