Hi! This type of equation is actully really simple to solve once you learn how so I'll only do a few and let you solve the rest.
To solve 3x + 6 = 18 you just need to remember that whatever action you do on one side of the equal sign you have to do on the other as well, and you just need to get the variable isolated on one side and the constant on the other.
So subtract 6 from both of the constants (6 and 18) to get to 3x = 12.
Then divide both sides by 3 to isolate x and you get x = 4.
To solve x/7 -9 = -7 you have to add 9 to both sides to get x/7 = 2. Then because it's a fraction with a denominator of 7 you multiply both sides by 7 to get x = 14.
To solve 8x - 2x = -36 you combine like terms to get 6x = -36 then divide both sides by 6 to get x = -6.
Hope this is what you were looking for and explained in an understandable way, if not I apologize. :)
