Пошаговое объяснение:
1) 2/5 - 6/12 = 24/60 - 30/60 = -6/60 = -1/10
2) 3. 12/36 * (-1/10) =
3. 1/3 * (-1/10) = 10/3 * (-1/10) = -1/3
3) 3 : 1. 1/2 = 3 : 3/2 = 3 * 2/3 = 6/3 = 2
4) -1/3 - 2 = -2. 1/3
