Explanation:

- Soham's initial expenditure and savings are in the ratio of 5:1. Let's express this ratio in terms of variables: initial expenditure (5x) and initial savings (1x).

- His income (6x) increases by 25%. Thus, his new income is 1.25 times his initial income.

- His savings increase by 20%, making his new savings 1.2 times his initial savings.

- His new expenditure, therefore, can be calculated as: new income - new savings = 1.25 * (5x + x) - 1.2 * x.

- With the current expenditure known as Rs4,347, we can find the value of x.

- Solving the equation, we find that the initial income was Rs4,140.

- Option 2: Rs4,140 is the correct answer.