Hehe, a simple math problem! You can set unknown to solve! Solve the problem as follows:

Solution: Let Zhao Gang run for x seconds at a speed of 6m/s, and for y seconds at a speed of 8m/s, then 5Y is his sprint distance from the finish line.

6X+8Y=400

X+Y=65( 1 min 5 sec)

solve

X=60 seconds

Y=5 seconds

5Y=40, that is, when he is 40 meters away from the finish line, he sprints at a speed of 8 meters per second.

Do you understand, my friend? !