90. The fast train and the slow train travel in opposite directions from A and B respectively. After meeting, they moved on. When the distance between two trains is 2 10 km, the express train will travel 3/4 of the whole journey and the local train 3/5 of the whole journey. How many kilometers is it between A and B?

Solution: The distance between Party A and Party B = 3/5-(1-3/4) = 3/5-1/4 = 7/20.

Distance between Party A and Party B = 2 10/(7/20) = 600km.

9 1. It takes five hours for the bus to go from Station A to bilibili, and seven hours for the truck to go from bilibili to Station A. Two cars leave from two stations at the same time, and the truck stops for two hours. When they met, how many more miles did the bus walk than the truck?

Solution: Bus speed = 1/5, truck speed = 1/7.

The truck stops for 2 hours.

Then, if the bus travels for 2 hours, it is the whole journey 1/5×2=2/5.

The whole journey of two cars 1-2/5=3/5.

Distance ratio of bus and truck = speed ratio = inverse ratio of time = 7: 5.

Then as soon as they met, the bus * * * made 2/5+3/5× 7/12 = 2/5+21/60 = 3/4.

The truck has moved 1-3/4= 1/4.

Then there are 3/4 more buses than trucks-1/4 =1/2.

93. Party A and Party B walk along the railway at the same speed. A train passes by Party A, which takes 8 seconds. Five minutes later, the train passed by Party B, which took seven seconds. After the train meets Party B, how long will it take for Party A and Party B to meet?

Take the train length as 1.

The speed difference between cars and people is 1/8.

The sum of the speeds of vehicles and people is 1/7.

Vehicle speed: (1/8+1/7) ÷ 2 =15/12.

Human speed: (1/7-1/8) ÷ 2 =112.

When the car leaves Party A, the distance between Party A and Party B is:

( 15/ 1 12+ 1/ 1 12)×5×60=300/7

Meet the demand:

300/7 ÷ (1112+112) = 2400 seconds.

From car meeting B to car meetings A and B, you need:

2400-5×30=2 100 second =35 minutes.

for reference only