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1) 6x^2 - 2x + 18x - 6 - 6x^2 + 6x - 2x + 2 = - 24

16x - 6 + 4x + 2 = - 24

20x = - 20

x = - 1

2) 3x^2 + 9x - 15x - 45 - 3x^2 + 21x + x - 7 = 12 + 8x

-6x - 45 + 22x - 7 = 12 + 8x

16x - 8x = 52 + 12

8x = 64

x = 8