уменьшаемое - вычитаемое = разность
(80 + 20) - 12 = 100 - 12 = 88
(100 - 10) - 52 = 90 - 52 = 38
60 - (41 + 8) = 60 - 49 = 11
50 - (24 + 20) = 50 - 44 = 6
(70 + 30) - 45 = 100 - 45 = 55
