Раскрыть скобки и : 1)7a-(5a+4b) 2)9x-(7y-4x) -+3b) 4)8x-(3y+-x)

1) = 7a - 5a - 4b = (7a - 5a) - 4b = 2a - 4b
2) = 9x - 7y + 4x = (9x + 4x) - 7y = 13x - 7y
3) = - 2a + 3b + a - 3b = (-2a + a) + (3b - 3b) = - a
4) = 8x - 3y - 5x + 2y + x = (8x - 5x + x) - (3y - 2y) = 4x - y