Xiaoming runs twice and uncle runs three times.

Xiaoming's speed is 2/3 meters per second.

∴ Germany: 2x/3x32+32x = 400

The solution is X=7.5.

Uncle's speed is 7.5m/s.

Xiaoming's speed is 5m/s.

Uncle runs one lap more than Xiaoming.

Suppose: * * * takes x seconds.

∴ 7.5x=5x+400。

x= 160