Given, Speed of first dog = 30 km/hr Speed of second dog = 40 km/hr Formula: Speed = distance/time Relative speed, if two objects running opposite directions = Sum of speed of both objects Calculation: Relative speed, if both dogs running opposite directions = 30 + 40 = 70 km/hr ∴ Distance between them after 2 hrs = 70 × 2 = 140 km