Explanation:

- A and B together earn Rs. 90,000 each month.

- A saves 25% of his salary because he spends 75% of it.

- B saves 20% of his salary because he spends 80% of it.

- Both A and B have the same savings.

- Let's denote A's salary as 'x' and B's salary as 'y'. That gives us:

- x + y = Rs. 90,000

- 0.25x = 0.20y (because their savings are equal)

- Solving these two equations, we substitute:

- x = 0.8y

- Substitute x in x + y = 90,000:

- 0.8y + y = 90,000

- 1.8y = 90,000

- y = 50,000

- x = 90,000 - 50,000 = 40,000

- Difference in salary: 50,000 - 40,000 = Rs. 10,000

- Correct Answer: Option 2, Rs. 10,000