A car from a to B, 45 km per hour, 6 / 5 hours to arrive. If the speed is increased by 20%, then it can arrive in a few hours

A car from a to B, 45 km per hour, 6 / 5 hours to arrive. If the speed is increased by 20%, then it can arrive in a few hours

45x6 / 5 △ [45x (1 + 20%)]
=54÷54
=1 (hour)

If the speed of a car is 40km / h in the first half of the journey and 60km / h in the second half of the journey, the average speed of the whole journey is______ (2) if the speed in the first half is 40 km / h and that in the second half is 60 km / h, the average speed in the whole process is 40 km / h______ ．

(1) Suppose the distance from a to B is 2S, the time for the first half of the journey: T1 = sv1 = s40km / h; the time for the second half of the journey: T2 = SV2 = s60km / h; the time for the whole journey: T = T1 + T2 = s40km / H + s60km / h = s24km / h; the average speed for the whole journey: v = 2st = 2ss24