If there is a negative exponent, just flip them over for that exponent to be positive. Example: x^-3 would be 1/x³. Thus,
1. 2b²/5a^4
2. (5a³n)³
Distribute the exponent 3 to each term.
5³a^9n³ = 125a^9n³
3. (x^n+5/y)²
Distribute the exponent 2 to each term.
x^(2n) + 5²/y²
x^(2n) + 25/y²