Answer:
(3x + 5y)(9x² - 15xy + 25y²)
Explanation:
27x³ + 125y³ ← is a sum of cubes and factorises in general as
a³ + b³ = (a + b)(a² - ab + b²)
then
27x³ + 125y³
= (3x)³ + (5y)³ → with a = 3x and b = 5y
= (3x + 5y)((3x)² - 3x(5y) + (5y)² )
= (3x + 5y)(9x² - 15xy + 25y²) ← in factored form