Seven netball teams played in a school's competition. Each team had 7 players. If 3/7 of the number of players were disqualified for poor conduct, how many pupils were qualified?

28 players.

We know that there are seven teams with seven players each. This is 49 players total. We know that the fraction 3/7 must be equal to x/49. Since we multiples the denominator by 7, we have to multiply the numerator by 7 too. This is 3 x 7 =21. Therefore, 21 out of the 49 players were disqualified. However, the question wants to know how many qualified, so we must subtract. 49-21=28 players. Hope this helped!