Ethan is 25 years older than his daughter. 5 years from now, his daughter will be ¹₂ of his age while his son will be ²₅ of his daughter. Express his son’s present age as a fraction of Ethan's present age. Leave your answer in its simplest form.

	Ethan	Ethan's daughter	Ethan's son	Difference between Ethan and Ethan's daughter
Before	10 u - 5	5 u - 5	2 u - 5	25
Change	+ 5	+ 5	+ 5
After	2x5	1x5
		5x1	2x1
Comparing Ethan, his daughter and his son in the end	10 u	5 u	2 u	5 u

The repeated identity is the age of Ethan's daughter. LCM of 1 and 5 is 5.

The difference in age between Ethan and Ethan's daughter remains unchanged.

Difference in age between Ethan and Ethan's daughter
= 10 u - 5 u 
= 5 u 

5 u = 25

1 u = 25 ÷ 5 = 5

His son's present age 
= 2 u - 5
= 2 x 5 - 5
= 10 - 5
= 5

Ethan's present age
= 10 u - 5
= 10 x 5 - 5
= 50 - 5
= 45

His son's present age as a fraction of Ethan's present age
= ⁵₄₅
= ¹₉

Answer(s): ¹₉