The mathematical expression given is:

$9 + 7 \times (4 + 2) =$

To solve this, follow the order of operations, commonly known as PEMDAS (Parentheses, Exponents, Multiplication and Division (from left to right), Addition and Subtraction (from left to right)):

1. Parentheses first: $4 + 2 = 6$

2. Then multiplication: $7 \times 6 = 42$

3. Finally, addition: $9 + 42 = 51$

So, the final result is:

$9 + 7 \times (4 + 2) = 51$

Would you like more details or have any questions?

Here are five related questions you might find useful:

1. What is the order of operations, and why is it important in solving mathematical expressions?
2. How would the expression change if the parentheses were around $9 + 7$ instead of $4 + 2$?
3. How does understanding the distributive property help in simplifying expressions?
4. What are some common mistakes people make when applying the order of operations?
5. Can you explain how to solve an expression with both exponents and parentheses?

Tip: Always carefully check for parentheses and apply the correct operations in the proper order to avoid errors in solving mathematical expressions.