Ответ:

1) 2/3(x + 9) = 1/6x + 2

2/3x + 6 = 1/6x + 2

4/6x - 1/6x = 2 - 6

0,5x = -4

x = -8

2) 3x + 9x - 1/20 = 21 - 3x + 4/5

12x + 3x = 21 + 4/5 + 1/20

15x = 420/20 + 16/20 + 1/20

15x = 437/20

x = 437/20 : 15

x = 437/ 20 * 1/15

x = 437/300