1) 5/6 + 0,25 = 5/6 + 1/4 = 10/12 + 3/12 = 13/12
2) 4 1/3 : 13/12 = 13/3 * 12/13 = 4
3) 7/12 - 2/15 = 35/60 - 8/60 = 27/60 = 9/20
4) 9/20 : 0,9 = 9/20 : 9/10 = 9/20 * 10/9 = 1/2
5) 4 : 1/2 = 4 * 2 = 8
6) 7/12 + 1/9 = 21/36 + 4/36 = 25/36
7) 25/36 * 3,6 = 25/36 * 36/10 = 5/2
8) 5/8 - 1/3 = 15/24 - 8/24 = 7/24
9) 7/24 * 1 5/7 = 7/24 * 12/7 = 1/2
10) 5/2 : 1/2 = 5/2 * 2 = 5
11) 8 - 5 = 3
ответ: 3