4. Vitya and Vova collected 27 kg of waste paper together. If the number of kilograms of waste paper collected by Vitya were increased by 5 times, and that collected by Vova by 3 times, they would have 111 kg together. How many kilograms did each boy collect?
4. If the number of kilograms of waste paper collected by the two boys is tripled, we would get $81 (27 \cdot 3=81)$. Then $111-81=30$ (kg) is the doubled number of kilograms of waste paper collected by Vitya, which means Vitya collected 15 kg $(30: 2=15)$, then Vova - 12 kg $(27-15=12)$.