A has Rs. 10, which is 80% of the bus fare for two persons. This means the full fare for two tickets is: Full fare = $10 / 0.8 = 12.5$

B has Rs. 3, which he hands over to A. Therefore, A now has: Total money A has = $10 + 3 = 13$

The full fare for two tickets is Rs. 12.5. After paying for the two tickets, A will be left with: $13 - 12.5 = 0.5$ Thus, after buying the two tickets, A will be left with 0.5 (Rs. 50 paise).