Given:

• Arjun is 25 years younger than his mother.
• Arjun’s brother was born in 1964 and is 35 years younger than their mother.

We want: Arjun’s birth year.

Step 1: Calculate the mother's birth year:

$$1964 + 35 = 1999$$ So, the mother was born in 1999.

Step 2: Arjun is 25 years younger than his mother:

$$1999 - 25 = 1974$$ Therefore, Arjun was born in 1974.

✅ Final Answer: Arjun was born in 1974