8 + 21 - 4 - 13x + 6 = 0

- 13x = - 8 - 21 + 4 - 6

- 13x = - 31

x = 31/13

Объяснение:

2*4 + 7*3 - 2*2 - 13х + 6 = 0

8 + 21 - 4 - 13х + 6 = 0

31 - 13х = 0

-13х = -31

х = -31 : (-13)

х = 31//13

х = 2. 5/13