A tourist walks from 2 pm to 7 pm. He took the flat road first, and then returned to the starting point along the original road after reaching the top of the mountain. It is understood that he walks a

A tourist walks from 2 pm to 7 pm. He took the flat road first, and then returned to the starting point along the original road after reaching the top of the mountain. It is understood that he walks a flat road of 4 kilometers per hour. Solution: Suppose there is xkm on the horizontal road and ykm on the slope road. According to the meaning of the question, the traveler walked for five hours.

Available equation:? x/4+？ y/3+？ y/6+？ x/4=5，

Solution: x+y= 10(km),

Then the distance traveled by a traveler is: 2(x+y)=20(km).

So the answer is:

20