21/22*22/23*23/24*25/25*26/27*27/28*28/29*29/30
Сокращаем 22 и 22, 23 и 23, 24 и 24, 25 и 25, 26 и 26, 27 и 27, 28 и 28, 29 и 29. Получаем дробь:
21/30
ОТВЕТ: 21/30
21/22*22/23*23/24*25/25*26/27*27/28*28/29*29/30
Сокращаем 22 и 22, 23 и 23, 24 и 24, 25 и 25, 26 и 26, 27 и 27, 28 и 28, 29 и 29. Получаем дробь:
21/30
ОТВЕТ: 21/30