Answer - 1,

6x - 9 = 9

6x = 9 - (-9)

6x = 9 + 9

6x = 18

x = 18/6

x = 3

Answer - 2,

8x + 4 = 28

8x = 28 - 4

8x = 24

x = 24/8

x = 3

Answer - 3,

-7x - 4 = 17

-7x - 4 = 17

-7x = 17 - (-4)

-7x = 17 + 4

-7x = 21

-x = 21/7

-x = 3

Please it's a humble request mark it as Brainliest it tooks a lot of time to solve on mobile