a) 4x - 5y - 15x + 4y = (4x - 15x) + (-5y + 4y) = -11x - y
б) 5(6a + 1) - 8 = 30a + 5 - 8 = 30a - 3
в) 13x - (x - 9) + (5x + 6) = 13x - x + 9 + 5x + 6 = 17x + 15
a) 4x - 5y - 15x + 4y = (4x - 15x) + (-5y + 4y) = -11x - y
б) 5(6a + 1) - 8 = 30a + 5 - 8 = 30a - 3
в) 13x - (x - 9) + (5x + 6) = 13x - x + 9 + 5x + 6 = 17x + 15