Factorize : \( 64a^3 + 125b^3 + 240a^2b + 300ab^2 \)

\[ 64a^3 + 125b^3 + 240a^2b + 300ab^2 \] \[ = 64a^3 + 240a^2b + 300ab^2 + 125b^3 \] \[ = (4a)^3 + 3(4a)^2(5b) + 3(4a)(5b)^2 + (5b)^3 \] \[ = (4a + 5b)^3 \]