(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 7/12,
2) 5 7/12 : 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 = 23/4 - 19/6 = 69/12 - 38/12 = 31/12 = 2 7/12,
4) 2 7/12 : 15,5 = 31/12 : 155/10 = 31/12 * 10/155 = 2/12 = 1/6,
5) 5/6 + 1/6 = 6/6 = 1