According to the meaning of the question, when Xiaoming arrived at the sports ground, Xiaoli was 60*(5+3)=480 meters away from the sports ground.

It can also be said that from the time of departure to the time when Xiao Ming arrived at the sports ground, Xiao Ming walked 480 meters more than Xiao Li, and every minute Xiao Ming walked 20 meters more than Xiao Li, so we can know that the time from departure to the time when he arrived at the sports ground is 480/20=24 minutes.

Therefore, the distance from the school to the playground = 80 * 24 =1920m.

The second question:

Before B set out, A had walked 30 kilometers. At this time, the distance between the two cars is 330 kilometers.

From this time on, the distance traveled by Party A and Party B is counted as a sum, that is, in the end, two cars * * * walked 330+120 = 450km, and the total speed of the two cars was120km/h, so the time from Party A to Party A's last * * walk was 25 minutes.

The third question:

It's simple. Add up their speeds and calculate the comprehensive speed. Divide the total distance by the total speed.

(5 10-45*2)/(60+45)=4 hours