posted by Bella .
At football practice, players do a 20-minute warm-up before starting their practice drills. After the practice drills, they do a 10-minute cool-down. The expression 20+d+10 describes the length of practice, where d is the number of minutes the practice drills last. How long, in minutes, does practice last if 30 minutes are spent on practice drills.
Thank you for helping me.