To solve the expression $7\sqrt{5} - 2\sqrt{5}$:

1. Both terms have a common factor of $\sqrt{5}$.
2. You can factor out $\sqrt{5}$ from both terms:

$7\sqrt{5} - 2\sqrt{5} = (7 - 2)\sqrt{5}$

3. Simplify the expression inside the parentheses:

$(7 - 2)\sqrt{5} = 5\sqrt{5}$

So, the simplified expression is $5\sqrt{5}$.

Would you like more details or have any questions about this? Here are five related questions to expand on this topic:

1. How do you add or subtract like radicals?
2. What are the rules for simplifying expressions involving square roots?
3. How would you simplify $3\sqrt{2} + 4\sqrt{2}$?
4. What happens if the square roots have different radicands?
5. How would you multiply two radical expressions like $\sqrt{3} \times \sqrt{12}$?

Tip: Always look for common factors when simplifying radical expressions to combine like terms easily.