[ Rule of product ]

a) In Wonderland, there are three cities $A, B$, and $C$. There are 6 roads from city $A$ to city $B$, and 4 roads from city $B$ to city $C$.

How many ways are there to travel from $A$ to $C$?

b) In Wonderland, they built another city $D$ and several new roads - two from $A$ to $D$ and two from $D$ to $C$.

How many ways are there now to get from city $A$ to city $C$?
б) $K 6 \cdot 4=24$ old methods were added with $2 \cdot 2=4$ new ones.

## Answer

a) 24; b) 28 ways.