Вычеслите: 7/10 + 2/15 + 11/30 3/5 : (9/10 - 3/5 * 8/9)

1.
7/10 + 2/15 + 11/30 = 21/30 + 4/30 + 11/30 = 36/30 = 12/10 = 1 1/5 (или 1,2),
2.
3/5 : (9/10 - 3/5 * 8/9) = 6,
1) 3/5 * 8/9 = 24/45 = 8/15,
2) 9/10 - 8/15 = 27/30 - 24/30 = 3/30 = 1/10,
3) 3/5 : 1/10 = 3/5 * 10/1 = 30/5 = 6