tolong bantuannya beserta caranya

100% = basket + renang + voli + badminton + futsal
100% = 30% + 15% + 20% + 10% + futsal
100% = 75% + futsal
  25% = futsal

 20% = 28 orang
100% = 28 x 5
          = 140
futsal = 140 x 25%
          = 35 orang