Сравняем:
2/3 + 3/5 = (102/3) / 10 + (63/5) / 6 = 20/30 + 18/30 = 38/30 = 19/15
1/4 + 3/7 = (71/4) / 7 + (43/7) / 4 = 7/28 + 12/28 = 19/28
Таким образом, 2/3 + 3/5 > 1, а 1/4 + 3/7 < 1.
Сравняем:
2/3 + 3/5 = (102/3) / 10 + (63/5) / 6 = 20/30 + 18/30 = 38/30 = 19/15
1/4 + 3/7 = (71/4) / 7 + (43/7) / 4 = 7/28 + 12/28 = 19/28
Таким образом, 2/3 + 3/5 > 1, а 1/4 + 3/7 < 1.