Past Simple, Past Continuous et calcul des chevaliers

Complete the passage using the Past Simple or Past Continuous. Use the Past Simple for completed historical events and the Past Continuous for background actions in progress.

'King Arthur (be) ________ a legendary leader. While he (ride) ________ through the forest, he (find) ________ the magical sword in a stone. Knights (gather) ________ at the Round Table while Arthur (prepare) ________ for the battle. People (think) ________ that he (bring) ________ peace to Britain.'

Additional Logic Task: The legend states that the Round Table had seats for a specific number of knights. If the total number of knights $N$ is defined by the equation $N = (5 \times 3) + (2 \times 6) - 3$, calculate the number of knights at the table.