The mathematical expression in the image is:

$18 \div (5 + 4) \cdot 5^2 - 7^2$

Step-by-step solution:

1. Parentheses: $5 + 4 = 9$

   Now the expression becomes: $18 \div 9 \cdot 5^2 - 7^2$

2. Exponents: $5^2 = 25 \quad \text{and} \quad 7^2 = 49$

   Substituting these values: $18 \div 9 \cdot 25 - 49$

3. Division and Multiplication (left to right):

   • First, divide: $18 \div 9 = 2$
   • Then multiply: $2 \cdot 25 = 50$

   Now the expression is: $50 - 49$

4. Subtraction: $50 - 49 = 1$

Final Answer:

$\boxed{1}$

Would you like further clarification or additional examples?

5 Related Questions:

1. What are the rules of the order of operations (PEMDAS/BODMAS)?
2. How do exponents affect the order of operations in a complex expression?
3. How does dividing by a sum inside parentheses differ from dividing each term individually?
4. What happens if parentheses are missing in an expression like this?
5. Can you demonstrate a similar problem with higher exponents or more terms?

Tip:

Always evaluate expressions inside parentheses first and handle exponents before multiplication or division.