Question

A is twice as old as B. Ten years ago, A was four times as old as B. What are their present ages?

• A. 24 and 12
• B. 30 and 15
• C. 32 and 16
• D. 20 and 10

Answer 1

The correct option is B 30 and 15

Let B's age be x years. Then A's age is 2x years.
Ten years ago, their ages were, respectively, x-10 and 2x -10 years. Thus, we have
$2x-10=4(x-10)$

$2x-10=4x-40$
$2x=30$
$\therefore x=15$
So, B is 15 years old and A is 30 years old.