My friend Tom lives on Sun Street. It is near his school. He usually goes to school on foot. But sometimes he goes to school by bike. His father is a doctor. He goes to work by car. His mother is a teacher. She teaches English. She goes to work by metro. Today is Sunday. Tom doesn't have any lessons. He wants to go to Nanjing by train.

某旅行社组织一批游客外出旅游，原计划租用45座客车若干辆，但有15人没有座位；若租用同样数量的60座客车，则多出一辆车，且其余客车恰好坐满．已知45座客车租金为每辆220元，60座客车租金为每辆300元，问：

（1）这批游客的人数是多少？原计划租用多少辆45座客车？

（2）若租用同一种车，要使每位游客都有座位，应该怎样租用才合算？

关于地球所处的宇宙环境的叙述，正确的是（　　）