Answer:
5^20
Explanation:
since you have brackets around (5^5) you can multiply the exponents. if you think about it what you're essentially doing is
(5 * 5 * 5 * 5 * 5) * (5 * 5 * 5 * 5 * 5) * (5 * 5 * 5 * 5 * 5) *
(5 * 5 * 5 * 5 * 5)
which is why you can multiply the exponents to simplify