1. Calculate price per kg for each option:
- Весна: 1200/10 = 120 rub/kg
- Ромашка: 1700/15 ≈ 113.33 rub/kg
- Универсальный: 650/5 = 130 rub/kg
- Хозяюшка: 750/6 = 125 rub/kg
2. The cheapest option is 'Ромашка' at approximately 113.33 rub/kg.
3. Total cost for 120 kg: 120 kg * 113.33 rub/kg ≈ 13600 rubles.