The ratio of Rohan’s age 4 years ago and Rahul’s age after 4 years is 1 : 1. If at present, the ratio of their ages is 5 : 3, then find the ratio between Rohan’s age 4 years hence and Rahul’s age 4 years ago.

If ages in the numerical are mentioned in the ratio A : B, then A: B will be Ax and Bx
1) At present : Ratio of their ages = 5 : 3. Therefore, 5 : 3 will be 5x and 3x.
Rohan's age 4 years ago = 5x – 4
Rahul's age after 4 years = 3x + 4

2)Ratio of Rohan’s age 4 years ago and Rahul's age after 4 years is 1: 1
Therefore,
(5x - 4)/(3x + 4) = 1/1
⇒ 5x - 4 = 3x + 4
⇒ 5x - 3x = 4 + 4
⇒ 2x = 8
⇒ x = 4
Solving, we get x = 4

3)We are asked to find the ratio between Rohan's age 4 years hence and Rahul's age 4 years ago.
Rohan's age : (5x + 4)
Rahul's age: (3x – 4)
Ratio of Rohan's age and Rahul’s age
(5x + 4)/(3x - 4) = 24/8
(5x + 4)/(3x - 4) = 3/1
(5x + 4) : (3x - 4) = 3 : 1.