Xiao Ming and Xiao Hua practice running on a 400 meter circular road. They start from the same point and walk in the same direction at the same time. Xiao Ming runs 3.5 meters per second, and Xiao Hua runs 5.5 meters per second, After how many seconds. Two people meet for the second time?

Xiao Ming and Xiao Hua practice running on a 400 meter circular road. They start from the same point and walk in the same direction at the same time. Xiao Ming runs 3.5 meters per second, and Xiao Hua runs 5.5 meters per second, After how many seconds. Two people meet for the second time?

It's very easy to calculate. You set the number of seconds x, and then since you start in the same direction and meet at last, it must be the fast people who catch up with the slow people from behind, that is, Xiaohua is one lap ahead of Xiaoming, that is 400 meters. So the final formula is 5.5x-3.5x = 400, x = 200

Xiao Ming and Xiao Hua practice running on a 400 meter circular road. They start from the same place at the same time and go in opposite directions. Xiao Ming runs 4.5 meters per second
Xiaohua runs 5.5 meters per second. After a few seconds, they meet for the second time? (solving equation)

Let x seconds pass
（4.5+5.5）x=400x2
10x=800
x=80

Xiao Ming and Xiao Hua practice running on a 400 meter circular road. They start from the same point at the same time and walk in opposite directions. Xiao Ming runs 4.5 meters per second and Xiao Hua runs 4.5 meters per second
5.5 meters. After how many seconds. The two met for the second time?

80 seconds