Let \( x \) represent the number of games Ahmadullah's basketball team played last season. According to the problem, this season they will play 21 games, which is 12 games more than last season. This can be expressed in the equation:
\[ x + 12 = 21 \]
To find \( x \), we can solve the equation:
- Subtract 12 from both sides:
\[ x = 21 - 12 \]
- Simplify:
\[ x = 9 \]
Therefore, Ahmadullah's basketball team played 9 games last season.