Ankush and Bittu started a business together, where Ankush invested Rs. 'p' and Bittu invested Rs. 'p + 3000' initially. After 4 months, Ankush increased his investment by Rs. 3,000, while Bittu reduced his investment by Rs. 2,000. At the end of the year, the total profit was Rs. 83,000, and Ankush's share of the profit was Rs. 42,000. Determine the initial investment made by Bittu