The ratio of the present ages of two boys is 3:4. After

The ratio of the present ages of two boys is 3:4. After 3 years, the ratio of their ages is equal to will be 4:5.The ratio of their ages after 21 years will be

Let the ages of boys be 3x and 4x years respectively.
According to the question,
After 3 years

3x + 3	=	4
4x + 3	=	5

⇒ 16x + 12 = 15x + 15
⇒ 16x – 15x = 15 – 12
⇒ x = 3

∴ Required ratio after 21 years =	3x + 21
	4x + 21

3 × 3 + 21	=	9 + 21
4 × 3 + 21	=	12 + 21

30	=	10
33	=	11