Answer
$6\sqrt[3] {5}$
Work Step by Step
In order to simplify a cube root, we consider the factors of the number inside of the cube root. If any of these factors are perfect cubes, meaning that their cube root is an integer, then we can simplify the expression. We know that 8 and 5 are factors of 40. We know that 8 is a perfect cube, so we simplify:
$3\sqrt[3] {8} \sqrt[3] {5}=6\sqrt[3] {5}$
