數學題-想幫忙列式

請幫幫忙列式
1. Car A and Car B are approaching each other from Town X and Town Y 300km apart, driving at 50 km/h and 70 km/.h respectively.
a.Hong long will it take them to meet?
b.How far is their meeting place from Town X?
c.
2. Car ‘S and Car T were having a race. Car S was behind Car T, but was getting 5 km closer every hour. If the speed of Car T was 72 km/h, what was the speed of Car S?

3.Peter and David had a race. Peter’s running speed was 7 m/s while David’s was 9 m/s. They start off at the same time. How far apart were they after 5 seconds?