Arman, Narek and Areg are brothers. Arman's age is five times as much as Areg's age and Narek is 12 years elder than Areg. If Narek is 15 years old, how old are Areg and Arman?

Armans age : x
Aregs age: y

X = 5y
(15 - 12) = y. They said narek is 12 years older than areg so you deduct 12 years from nareks age which is 15.

So therefore y = 3. So Areg is 3 years old.

Since we know that y = 3
X = 5(3)
X = 15

So therefore Arman is 15 years and Areg is 3 years.