solve:

x -8 = 4
+ 8 +8
x = 12

my answer is x = 12

solve:
80 = 10x
-- ---
10 10

8 = x

my answer is x =8

solve:
3x= -12
-- ---
3 3

x = -4

my answer is x = -4

Solve:
12 -3x = 9
-12 -12
-3x = -3
--- ---
-3 -3

x = 1

my answer is x = 1

ok on all of them.

Great job! Your answers are correct.

To solve these equations, you used the method of combining like terms and isolating the variable on one side of the equation.

Let's go through each equation to see how you arrived at the answer:

1. x - 8 = 4:
- To isolate the variable, you added 8 to both sides of the equation.
- This gave you x - 8 + 8 = 4 + 8, simplifying to x = 12.

2. 80 = 10x:
- To isolate the variable, you divided both sides of the equation by 10.
- This gave you 80/10 = 10x/10, simplifying to 8 = x.

3. 3x = -12:
- To isolate the variable, you divided both sides of the equation by 3.
- This gave you 3x/3 = -12/3, simplifying to x = -4.

4. 12 - 3x = 9:
- To isolate the variable, you subtracted 12 from both sides of the equation.
- This gave you 12 - 3x - 12 = 9 - 12, simplifying to -3x = -3.
- Then you divided both sides of the equation by -3.
- This gave you -3x/-3 = -3/-3, simplifying to x = 1.

By following these steps, you correctly solved each equation and found the value of x. Well done! Let me know if there's anything else I can assist you with.