Answer:
m = undefined
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Algebra I
- Slope Formula:

Explanation:
Step 1: Define
Point (-9, 15)
Point (-9, -8)
Step 2: Find slope m
Simply plug in the 2 coordinates into the slope formula to find slope m
- Substitute in points [SF]:

- [Fraction] Subtract/Add:

Here we see that our slope would be undefined since we cannot divide anything by 0.