Topic: When I finished half the distance, my father caught up with Xiaoming. When I caught up with him, Xiaoming still had a distance of 3/ 10 to walk.

Then it takes 7/ 10 for cycling and1/2-3/10 =1/5 for walking.

So the speed of cycling is (7/ 10)/( 1/5) = 3.5 times that of walking.

The last 3/ 10 distance was changed from walking to cycling, which was 5 minutes ahead of schedule. If the walking speed is V and the whole journey is 1, then

(3/ 10)/3.5v =(3/ 10)/v-5

Solution: v= 3/70

Time required for Xiao Ming to walk from home to school: 1/(3/70) = 70/3 minutes.