Упрощение выражений:

1. -2,1y + 7y = (-2,1 + 7)y = 4,9y
2. -2,5x + x = (-2,5 + 1)x = -1,5x
3. -a - 0,8a = (-1 - 0,8)a = -1,8a
4. $$\frac{1}{3}x - 2x = \frac{1}{3}x - \frac{6}{3}x = \left(\frac{1}{3} - \frac{6}{3}\right)x = -\frac{5}{3}x = -1\frac{2}{3}x$$ = -$$1\frac{2}{3}$$x
5. $$\frac{1}{2}a + \frac{1}{5}a = \frac{5}{10}a + \frac{2}{10}a = \left(\frac{5}{10} + \frac{2}{10}\right)a = \frac{7}{10}a$$ = $$\frac{7}{10}$$a
6. $$\frac{5}{6}b - b = \frac{5}{6}b - \frac{6}{6}b = \left(\frac{5}{6} - \frac{6}{6}\right)b = -\frac{1}{6}b$$ = -$$\frac{1}{6}$$b
7. -p - p - p - 3p - p - p = (-1 - 1 - 1 - 3 - 1 - 1)p = -8p
8. 4,14a + 8,73a + 5,8a - a = (4,14 + 8,73 + 5,8 - 1)a = 17,67a
9. x + y - x - y + 4 = (x - x) + (y - y) + 4 = 0 + 0 + 4 = 4
10. 5 - a + 4a - b - 6a = 5 + (-1 + 4 - 6)a - b = 5 + (-3)a - b = 5 - 3a - b
11. 1,2c + 1 - 0,6y - 0,8 - 0,2c = (1,2c - 0,2c) - 0,6y + (1 - 0,8) = c - 0,6y + 0,2 = c - 0,6y + 0,2
12. c - (a + b) = c - a - b = c - a - b
13. -c - (-a + b) = -c + a - b = -c + a - b
14. x - (a - b) + (c - d) = x - a + b + c - d = x - a + b + c - d
15. 10 - (a - b) - (c + d) = 10 - a + b - c - d = 10 - a + b - c - d