A cyclist goes uphill at 3km/hr & down the same hill at 6km/hr. What is the average speed?

Hello Kiara... dear, let x be the distance up the hill. So time to go up = x/3 h and to come down time = x/6 h
Total time taken for journey = x / 2 h
Total distance of journey = 2x
So average speed = 4 km p h