Answer:
y + 1 = -1/2(x - 8)
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
- Brackets
 - Parenthesis
 - Exponents
 - Multiplication
 - Division
 - Addition
 - Subtraction
 
Algebra I
Slope Formula: 

Point-Slope Form: y - y₁ = m(x - x₁) 
- x₁ - x coordinate
 - y₁ - y coordinate
 - m - slope
 
Explanation:
Step 1: Define
f(8) = -1 → Coordinate (8, -1)
f(6) = 0 → Coordinate (6, 0)
Step 2: Find slope m
- Substitute [SF]: 

 - Add/Subtract: 

 - Simplify: 

 
Step 3: Write Function
Substitute into general form.
- Point 1: y + 1 = -1/2(x - 8)
 - Point 2: y = -1/2(x - 6)