Correct Answer - Option 1 : Rs. 90000

Let, the salary of Mr. X be Rs**"Y".**

As per the question,

He spent 40% of his salary on food, 10% on clothes, 15% is house rent and investment is 20%.

Therefore, the correct spending will be:

⇒ 40% + 10% + 15% + 20%.

⇒ 85% of salary.

⇒ 0.85Y.

Now remaining salary will be:

⇒ Y - 0.85Y.

⇒ 0.15Y.

As the question, the remaining salary is Rs. 12900.

Therefore,

⇒ 0.15Y = 12900.

⇒ Y = 12900 ÷ 0.15.

⇒ Y = 86000.

As the value of Y is Rs.86000.

Therefore, the correct answer should be **"Option2: Rs. 86000".**