Mr. Karim borrowed Tk. 500 at 5% simple interest per year. After some time, he borrowed Tk. 400 at 3$\frac{1}{2}$% simple interest per year for the second time. Six months after the second time borrowing, he repaid both the borrowed money along with interest and the amount repaid was Tk. 994.50. How many years after the first time borrowing Mr. Karim repaid the borrowed money?