1. Find two tiles with the same picture.
2. Both must be free: a tile is free when nothing touches its left side, or nothing touches its right side.
3. Cross out both. Carry on until every tile is crossed out.

Take your time. If you get stuck, the answers are on the back.

Cross out the two tiles marked 1 first, then the two marked 2, and so on. Other orders can work too.