Answer:
x² - x + 4
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS 
- Brackets 
- Parenthesis 
- Exponents 
- Multiplication 
- Division 
- Addition 
- Subtraction 
Algebra I
Explanation:
Step 1: Define
(6x² - 10x + 9) + (-5x² + 9x - 5)
Step 2: Simplify
- Combine like terms (x²): x² - 10x + 9 + 9x - 5
- Combine like terms (x): x² - x + 9 - 5
- Combine like terms (Z): x² - x + 4