In a basketball game, the competition system is one game between two teams, with a total of 45 games, how many basketball teams participate in the game?

In a basketball game, the competition system is one game between two teams, with a total of 45 games, how many basketball teams participate in the game?

X teams participated in the competition
Then (x-1) x / 2 = 45
x=10
Ten teams took part in the competition