A teacher travelled a distance of 22km in 7 hours. He travelled partly on foot at the speed of 2km/h and partly on bicycle at the rate of 4km/h. The distance travelled on foot is:

Let the time travelled on foot be t hours.
Then, the time travelled on bicycle will be (7−t) hours.

We know that:

Distance=Speed×Time
Total distance is the sum of distances on foot and by bicycle:

Distance on foot+Distance on bicycle=22km
(2×t)+[4×(7−t)]=22
2t+28−4t=22
−2t=22−28
−2t=−6
t=3 hours
Therefore, the distance travelled on foot is:

Distance on foot=2km/h×3 hours=6km