Thank you to all that helped. Have finally work out the answer. Basically the answer comes out to 3 to the power or 3 over 8. You don’t mind if I don’t show you the working out, as it took me a while just to write out the question (equation) out in the Latex version.
It was the bracketed root that was the confusion, but you just had to think out side the box or brackets in this case.
Yet again many thanks.
Cha