Question

Five years ago , A was three times as old as B and then 10 years later, A shall be twice as old as B. What are the present ages of A and B ( in years) ?

• A. $45,15$
• B. $30,40$
• C. $50,30$
• D. $50,20$

Answer 1

Answer: (D)

$50,20$

Let the age of A be a, and age of B be b
Now, $a-5=3(b-5)$
$a=3b-10$ (1)
After 10 years,
$a+10=2(b+10)$
$a=2b+10$ (2)
From 1 and 2,
$3b-10=2b+10$
$b=20$
And, $a=2b+10=2\times 20+10=50$ years
Thus, age of A = 50 years and age of B = 20 years.