The ratio of present age of two brothers is 1 : 2 and 5 years back the ratio was 1 : 3. What will be the ratio of their age after 5 years?

Question: The ratio of present age of two brothers is 1 : 2 and 5 years back the ratio was 1 : 3. What will be the ratio of their age after 5 years?

Solution:
Let the present age of two brothers be x and 2x years.
Now, (x - 5)/(2x - 5) = 1/3
⇒ 3x - 15 = 2x - 5
⇒ 3x - 2x = 15 - 5
⇒ x = 10
Their present age is 10 and 20 years

After 5 years their required ratio = 15/25
= 3/5
= 3 : 5