∛(270x )-∛(10x^4)

subtract by simplifying by collecting like terms

∛(270x )-∛(10x^4)

= ∛27∛(10x) - ∛x^3∛(10x)
= 3∛(10x) - x∛(10x)
= (3-x)∛(10x)

Nice cube root symbol.
How did you do that?
Are you on a Mac or PC ?