Let's solve the expression step by step:

$6 \div 2 - \left(81 \div 3^2\right)$

1. Start with the exponent: $3^2 = 9$

2. Now divide 81 by 9: $81 \div 9 = 9$

3. Then divide 6 by 2: $6 \div 2 = 3$

4. Finally, subtract 9 from 3: $3 - 9 = -6$

So, the result of the expression is $-6$.

Would you like a deeper explanation or any further details?

Here are 5 related questions you might be interested in:

1. How does the order of operations affect solving expressions?
2. What are the rules for dividing numbers with exponents?
3. How do you solve more complex expressions involving parentheses?
4. What is the role of exponents in algebraic equations?
5. Can negative numbers change the outcome in more complicated expressions?

Tip: Always remember PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction) for the correct order of operations!