1 задание
а) + (5 - 2 - 7 + 4) = 5 - 2 - 7 + 4 = 9 - 9 = 0
б) - (12 - 6 + 17 - 10) = - (29 - 16) = -13
в) 20 + (7 - 11 + 8) = 20 + 4 = 24
г) 31 - (-9 + 40 - 50) = 31 - (-19) = 31 + 19 = 50
д) 12 - (5 + 6 - 2) = 12 - 9 = 3
2 задание.
а) -7 + (12 - 8) = -7 + 4 = -3
б) 19 + (3 - 2) = 19 + 1 = 20
в) -23 - (7 + 70) = -23 - 77 = -100
3 задание.
а) (-7 + 12) - 8 = 5 - 8 = -3
б) 19 + 3(-2) = 19 - 6 = 13
в) (-23 - 7) + 70 = -30 + 70 = 40
