Raju and Ramu went into a partnership for a year. Raju invests Rs.250 and Ramu invests some amount. After 7 months, Raju adds Rs.150 and Ramu removes Rs.150 to their respective investment. Total profit they had is RS.2800. The difference between their profit shares is Rs.300. Find the initial investment of Ramu. (Ramu share is 300 more than Raju)