A. B is 400 kilometers away from the two places. Car a and car B leave from the two places at the same time. Car a travels 38 kilometers per hour, and car B travels 42 kilometers per hour. A swallow starts to fly to car B at the same time with car a at the speed of 50 kilometers per hour. When it meets car B, it turns back to car A. how many kilometers did the swallow fly before the two cars can meet?

A. B is 400 kilometers away from the two places. Car a and car B leave from the two places at the same time. Car a travels 38 kilometers per hour, and car B travels 42 kilometers per hour. A swallow starts to fly to car B at the same time with car a at the speed of 50 kilometers per hour. When it meets car B, it turns back to car A. how many kilometers did the swallow fly before the two cars can meet?

The flying time of swallow is the meeting time of a and B vehicles, that is: 400 △ 38 + 42, = 400 △ 80, = 5 (hours); the flying distance of swallow: 50 × 5 = 250 (kilometers); a: the two vehicles can meet only after the swallow flies 250 kilometers

A and B start from two places at the same time and travel in opposite directions. A travels 45 kilometers per hour and B 32 kilometers per hour. When they meet, a travels 52 kilometers more than B. the distance between a and B is very long

Time required: 52 (45-32)
=52÷13
=4 hours
The distance between a and B: (45 + 32) × 4 = 308km

Party A and Party B ride from both places at the same time. Party A travels 20 kilometers per hour, and Party B travels 18 kilometers per hour. When they meet, the distance between them is 3 kilometers from the midpoint of the whole journey. How long is the whole journey? (draw a picture first, then answer)

3 × 2 (20-18) = 6 △ 2 = 3 (hours); (20 + 18) × 3 = 38 × 3 = 114 (kilometers); answer: the whole journey is 114 kilometers long

Party A and Party B are traveling from two places at the same time. After 4 hours, they meet at a distance of 4 kilometers from the midpoint. A is faster than B. how many kilometers is a faster than B per hour?

A: A is 2 kilometers faster than B per hour