3. 905 = □ + □ 820 = □ + □ 199 = □ + □ + □

Решение: \(905 = 900 + 5\) \(820 = 800 + 20\) \(199 = 100 + 90 + 9\) Ответ: \(905 = 900 + 5\) \(820 = 800 + 20\) \(199 = 100 + 90 + 9\)