The distance between station a and station B is 100 km. A car drives from station a to station B at the speed of 40 km / h, and the other station B starts at the same time every 15 minutes If the speed of a car is 20km / h, the car from station a can see () cars from station B along the way 【A】15 【B】10 【C】8

The distance between station a and station B is 100 km. A car drives from station a to station B at the speed of 40 km / h, and the other station B starts at the same time every 15 minutes If the speed of a car is 20km / h, the car from station a can see () cars from station B along the way 【A】15 【B】10 【C】8

100/40*60/15=10 B

A car drives from a to B at the speed of 40km / h, and after 3 hours, the speed is changed to 30km / h in case of rain, which is 45 minutes later than the original time, so as to find the distance between a and B
It can be solved in two ways

Let the time after rain be t. (45 minutes is equal to 3 / 4 hours). From the known meaning, we can get that: 30t + 40x3 = 40x (T + 3-3 / 4), we can get that t = 3 hours, and the distance is 210 kilometers

A car drives from a to B at the speed of 40km / h, and changes its speed to 30km / h after 3 hours due to rain. As a result, it arrives at B 45 minutes later than the original time. Find the distance between a and B, and use the equation to solve it

Solution: the distance between Party A and Party B is s km, and the car running time is t hours
40x3+30x(T-3+45/60)=S
40T=S
The solution is s = 150