(7 - 1 5/12) : 6,7 + (5,75 - 3 1/6) : 15,5 = 1
1) 7 - 1 5/12 = 6 12/12 - 1 5/12 = 5 целых 7/12 = 67/12
2) 67/12 : 6,7 = 67/12 : 67/10 = 67/12 * 10/67 = 10/12 = 5/6
3) 5,75 - 3 1/6 = 5 3/4 - 3 1/6 = 5 9/12 - 3 2/12 = 2 целых 7/12 = 31/12
4) 31/12 : 15,5 = 31/12 : 155/10 = 31/12 * 10/155 = (1*5)/(6*5) = 5/30 = 1/6
5) 5/6 + 1/6 = 6/6 = 1