# A discrete mathematics problem by Swadesh Rath

**Discrete Mathematics**Level 4

There are four basket-ball players A, B, C, D. Initially, the ball is with A. The ball is always passed from one person to a different person. In how many ways can the ball come back to A after seven passes? (For example A → C → B → D → A → B → C → A and A → D → A → D → C → A → B → A are two ways in which the ball can come back to A after seven passes.)