Question

There are 3 different roads from city A to city B and 2 different roads from city B to city C. In how many ways can someone go from city A to city C passing by city B?

Answer 1

$\text{Number of ways can someone go from}\\ \text{ city A to city C passing by city B}\\ =C_{1}^{3} \times C_{1}^{2}=3 \times 2 =6\; ways$