Пошаговое объяснение:
(a + b)*5 + 9a + 3b = 5a + 5b + 9a + 3b = 14a + 8b = 14*3 + 8*2 = 42+16 = 58
13*(a + b) - 7b + 4a = 13a + 13b - 7b + 4a = 17a + 6b = 17*3 + 6*2 = 51+12 = 63
6*(x + a) - 5a = 6x + 6a - 5a = 6x + a = 6*4 + 3 = 24 + 3 = 27
30x - (5x + 4x) = 30x - 5x - 4x = 21x = 21*4 = 84
