1. (3 si 2/6 + 1 si 5/7) * 1 si 2/3 = (⁷⁾20/6 + ⁶⁾12/7) * 5/3 = (140/42 + 72/42) * 5/3 =
212/42 * 5/3 = 1060/126 = 530/63
2. - 2x + 8 - 12 = - 20
- 2x = - 20 + 4
x = 16/2
x = 8
3. (3 si 2/8 + 1 si 5/6) :1/12 = (³⁾26/8 + ⁴⁾11/6) * 12 = (78/24 + 44/24) * 12 = 122/24 *
* 12 = 122/2 = 61
4. 5x - 30 + 10 = - 45
5x = - 45 + 20
5x = - 25
x = - 25/5
x = - 5
