GIVEN: Speed of A and B = 49 km/h and 51 km/h FORMULA USED: Relative Speed (in opposite direction) = Speed 1 + Speed 2 Time = Distance/Speed CALCULATION: Since, they walk in the opposite directions, their relative speed = 49 + 51 = 100 km/h Distance = 650 km Time = Distance/Speed = 650/100 = 6.5 hours = 6 hours 30 minutes