Answer:
Step-by-step explanation:
First, we need to know the number of player that don't stretch and the number of player that don't stretch and get injured.
So, the number of player that don't stretch are calculated as:
28 - 21 = 7
Because there are 28 footballers and 21 stretch regularly.
Additionally, the number of player that don't stretch and get injured are equal to:
8 - 3 = 5
Because there are 8 injured players and 3 of them stretch.
Finally, the fraction of players who don't stretch that get injured are:
Because there are 7 players that don't stretch and 5 of them get injured last year.