A salesperson used to get a commission of 9% of his total sales for a month.with a change in the terms of employment,he now gets a fixed amount of 3000 per month plus a commission of only 5% on the access of his sales over 10,000.if the difference in the amounts that he received last month and this month is 400 rupees,though the total sales were the same,what were the total sales this month?pl. provide sol. also

1) rs. 57,500
2) rs.52,500
3) rs.67,500
4) cannot be determined