A runs at the speed of 5km / h. After 2 hours, he starts from the same place and follows the same road to catch up with A. but they agree that B should catch up with a no later than 1 hour and no later than 1 hour and 15 minutes. How to determine the speed range of B's car? (use the equation)

Let the velocity of B be x, then the time taken by B to catch up with a is (5 × 2) / (X-5), and inequality can be obtained
1=

Xiao Wang's walking speed is 50% slower than his running speed, and his running speed is 50% slower than his cycling speed. If he rides from city a to city B, and then walks back to city a, it will take him 2 hours. Ask Xiao Wang if it takes () minutes to run from city a to city B
A. 45B. 48C. 56D. 60

Suppose the speed of cycling is x, then the speed of running is (1-50%) x, and the speed of walking is (1-50%) (1-50%) X. according to the equation, we can get the following result: 1 x + 1 (1 − 50%) (1 − 50%) x = 2, the solution is x = 52, the speed of running is 54, Xiao Wang needs 1 △ 54 = 45 hours = 48 minutes to run from city a to city B

On the 400 meter circular track, a practices cycling at a speed of 6 meters per second, and B practices running at a speed of 4 meters per second
How many seconds later did they meet for the first time

400 ÷ (6-4) = 200 (seconds)

After two hours, B starts from the same place and follows the same road to catch up with A. if B plans to catch up with a in one hour (including one hour), the slowest time is one hour and 15 minutes. Q: what range should b control his speed?

One hour to catch up
5*（2+1）/1 = 15 km/h
1 hour 15 minutes
5*（2+1.25）/1.25 = 13km/h
So it's between 13km and 15km per hour

A runs at the speed of 5km / h. After 2 hours, he starts from the same place and follows the same road to catch up with A. but they agree that B should catch up with a no later than 1 hour and no later than 1 hour and 15 minutes. How to determine the speed range of B's car? (use the equation)