Don't be confused by the extra clues in the topic.
For example, this question is about the distance that dogs run.
No matter what changes Xiao Ming or Xiao Ming's father have on the road.
The dog has been doing back and forth without any delay.
So the running distance of the dog = speed * time.
Now that the speed is known, we just need to find out the time.
Time is the time when Xiao Ming's father catches up with him after he goes out for a walk.
Time is on this issue.
=( 10*2)/(3-2)=20 seconds
So the distance = 20 * 5 = 100m.
If there are other circumstances in the question.
(For example, Dad Xiaoming forgot to bring his book when he went out, so he went home to get it.)
The solution is the same, just the total time.