Ответ:

1) -23,5

2) 3 74/75

Пошаговое объяснение:

1) 12-(20,5-15 1/3)-(15 2/3+3 1/6+11,5) = -23,5

1. 20,5 - 15 1/3 = 20 1/2 - 15 1/3 = 20 3/6 - 15 2/6 = 5 1/6

2. 15 2/3+3 1/6+11,5 = 15 2/3+3 1/6+11 1/2 = 15 4/6+3 1/6+11 3/6 = 30 2/6

3. 12 - 5 1/6 - 30 2/6 = 12 - 35 3/6 = -23 1/2 = -23,5

2) | 3 3/5-1 1/6-6.6 | -(-6.8+7.09)+(7.09-7.2) = 3 74/75

1.  | 3 3/5-1 1/6-6.6 |  = | 3 18/30-1 5/30-6 18/30 | = | -4 1/6|  = 4 1/6

2. -6.8+7.09 = 0,29

3. (7.09-7.2) = -0,11

4. 0,29 + (-0,11) = 0,29 - 0,11 = 0,18 = 9/50

5. 4 1/6-9/50 = 4 25/150-27/150 = 3 175/150-27/150 = 3 148/150 = 3 74/75