Let the salary be ₹ 100. So, after first increase is ₹ 10. Now, his salary is ₹ 110. Second increase is ₹ 22. Now the salary is ₹ 132. The third increase is ₹ 33. So, for initial salary of ₹ 100, the third increase is ₹ 33. Therefore, for an increase of ₹ 6600, the initial salary will be ₹ 20000. So, the second increase is ₹ 4400.