Пошаговое объяснение:
3/4 + (2 - 1 11/21) : 4/9 - 1 4/7 = 1/4
2 - 1 11/21 = 2 - 32-21 = (42-32) / 21 = 10/21
10/21 : 4/9 = 10/21 * 9/4 = 15/14
3/4 + 15/14 = (21+30) / 28 = 51/28
51/28 - 1 4/7 = 51/28 - 11/7 = (51-44) / 28 = 7/28 = 1/4
