Question

In 10 years , A will be twices as old as B was 10 years ago . if A is now 9 years older than B , The present age of B is​

Answer 1

Let present age of B be x years.

In 10 years, A will be twice as old as B was 10 years ago.

According to question,

⇒ A + 10 = 2(x - 10)

⇒ A + 10 = 2x - 20

⇒ A = 2x - 20 - 10

⇒ A = 2x - 30 ___ (eq 1)

Also, at present A is 9 years older than B

Means,

Present age of A = (x + 9) years

Substitute value of A = (x + 9) in (eq 1)

⇒ x + 9 = 2x - 30

⇒ x - 2x = -30 - 9

⇒ - x = - 39

⇒ x = 39

∴ Present age of B = 39 years

& Present age of A = 39 + 9

⇒ 48 years

•°• $\sf{\bold{\underline {Present \:age\:of\:B\:is\:39\:years}}}$

Answer 2

Answer:

$\bold\red{39\:years}$

Step-by-step explanation:

Let the present age of B be 'x' years.

Therefore,

Present age of A will be (x+9) years.

10 years ago from now,

Age of B = (x-10) years

Age of A = (x+9-10) = (x-1) years

Again,

After 10 years from now,

Age of B = (x+10) years

Age of A = (x+9+10) = (x+19) years

Now,

According to Question,

In 10 years , A will be twices as old as B was 10 years ago

=> x + 19 = 2(x-10)

=> x + 19 = 2x -20

=> 2x-x = 20 + 19

=> x = 39

Therefore, x = 39 years

Hence,

Present age of B = 39 years