70 : (5/8 + 5/6) + (3 1/9 - 1/3) = 50 7/9
1) 5/8 + 5/6 = 15/24 + 20/24 = 35/24
2) 3 1/9 - 1/3 = 2 10/9 - 3/9 = 2 7/9
3) 70 : 35/24 = 70 * 24/35 = 2 * 24 = 48
4) 48 + 2 7/9 = 50 7/9
Пояснения:
5/8 = 15/24 - доп.множ. 3
5/6 = 20/24 - доп.множ. 4
1/3 = 3/9 - доп.множ. 3