Answer:
-7
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS 
- Brackets 
- Parenthesis 
- Exponents 
- Multiplication 
- Division 
- Addition 
- Subtraction 
Equality Properties
Explanation:
Step 1: Define
4x - 12 ≤ 16 + 8x
Step 2: Solve for x
- Subtract 4x on both sides: -12 ≤ 16 + 4x
- Subtract 16 on both sides: -28 ≤ 4x
- Divide 4 on both sides: -7 ≤ x
- Rewrite: x ≥ -7
Here we see that any value x greater than or equal to -7 would work as a solution to the inequality. 
∴ our answer is -7.