Question

Question #97b73

Answer 1

2 or 4 ways, depending on whether or not the buses are numbered.

Explanation:

The best way to do this, at least for me, is to list all the possibilities.

Bus, Bus
4, 7
5, 6

There are only two ways to do it if you don't care about the order of buses.

Bus 1, Bus 2
4, 7
5, 6
6, 5
7, 4

There are 4 ways if you number the buses.