Question

At present, Ajay's age is twice that of Rohan's age. 8 years ago Ajay's age was 4 times Rohan's age that time. What will be Rohan's age after 6 years?

Answer 1

At present, A = 2 R
8 years ago, (A-8) = 4 (R-8)
substituting the value of A 
⇒(2R -8) = 4(R-8)
⇒2R = 24
⇒R = 12 years 
so, A = 24 years
After 6 Years , Rohan will be 12+6 = 18 years old

Answer 2

Let,
the present age of Ajay = x
the present age of Rohan = y
according, to the question,
x = 2y....(1)
before 8 years,
(x-8) = 4(y-8)......(2)
Sub (1) in (2)
⇒ (2y -8) = (4y - 32)
⇒ 2y -4y = -32 +8
⇒ -2y = -24
⇒ y = 12
therefore, present age of rohan = 12
Ajay's age after 6 years = 12 + 6 = 18 years