**1.** \(-9x+7x-5x+2x = (-9+7-5+2)x = -4x\)
**2.** \(5\alpha-6\alpha+2\alpha-10\alpha = (5-6+2-10)\alpha = -1\alpha = -\alpha\)
**3.** \(-3,8k-k+3,8k+k = (-3,8-1+3,8+1)k = -1k = -k\)
**4.** \(\alpha+6,2\alpha-6,5\alpha-\alpha = (1+6,2-6,5-1)\alpha = -0,3\alpha = -\frac{3}{10}\alpha\)
**5.** \(\frac{2}{9}m+\frac{4}{9}m-\frac{3}{9}m-\frac{5}{9}m = (\frac{2+4-3-5}{9})m = -\frac{1}{9}m\)
**6.** \(-18n-12n+7,3n+6,5n = (-18-12+7,3+6,5)n = -2,2n\)
**7.** \(-8x+5,2\alpha+3x+5\alpha = (-8+3)x+(5,2+5)\alpha = -5x+10,2\alpha\)
**8.** \(5\alpha-9,2m+7\alpha+15m = (5+7)\alpha+(-9,2+15)m = 12\alpha+5,8m\)
**9.**
\[\frac{2}{7}x-\frac{4}{9}y-\frac{5}{14}x+\frac{2}{3} = (\frac{2-5}{14})x-\frac{4}{9}y+\frac{2}{3} = -\frac{3}{14}x-\frac{4}{9}y+\frac{2}{3}\]
**10.** \(-6a+5a-x+4x = (-6+5)a+(-1+4)x = -a+3x\)
**11.** \(23x-23+40+4x = (23+4)x-23+40 = 27x+17\)
**12.** \(4x-2a+6x-3a+4 = (4+6)x-(2+3)a+4 = 10x-5a+4\)
**Ответы:**
1. -4x
2. -\alpha
3. -k
4. -\frac{3}{10}\alpha
5. -\frac{1}{9}m
6. -2,2n
7. -5x+10,2\alpha
8. 12\alpha+5,8m
9. -\frac{3}{14}x-\frac{4}{9}y+\frac{2}{3}
10. -a+3x
11. 27x+17
12. 10x-5a+4