A and B start from AB, and a travels 40 kilometers per hour. B takes 7 hours to complete the whole journey. When the two cars meet, a travels four seventh of the whole journey, How many kilometers is ab distance? All right, give me extra points (base 50 points)

A and B start from AB, and a travels 40 kilometers per hour. B takes 7 hours to complete the whole journey. When the two cars meet, a travels four seventh of the whole journey, How many kilometers is ab distance? All right, give me extra points (base 50 points)

When we met, B made 1-4 / 7 = 3 / 7 of the whole journey
Meeting time: 3 / 7 △ 1 / 7 = 3 hours
AB distance: 40 × 3 △ 4 / 7 = 210 km

Party A and Party B set out from two places 75KM apart, but they are facing each other. Party A travels 10km per hour, 2km faster than Party B. Party B starts first. When they are 5km apart, how many hours has Party B traveled

【75-（10-2）×2-5】÷（10+10-2）+2
=54÷18+2
=3+2
=5 hours

Party A and Party B are walking towards each other. Party A is 4.8km per hour and Party B is 4.4km per hour. After 2.5 hours, the distance between Party A and Party B is 31.5km. How many kilometers is the distance between the two cities?

(4.8 + 4.4) * 2.5 + 31.5 = 54.5km