(root(4)5)/(4*root(4)27), we first want to remove the radicals from the denominator, we can do this by multiplying by root(3/4)27/root(3/4)27 which is equal to 1.
(root(4)5)/(4*root(4)27) * root(4)27^3/root(4)(27)^3 = (root(4)5*root(4)27^3)/(4*root(4)27*root(4)27^3) = (root(4)5*root(4)27^3)/(4*root(4)27^4) = (root(4)5*root(4)27^3)/(4*27)
=(root(4)5*root(4)27*root(4)27*root(4)27)/108 = (root(4)(5*27^3))/108 =(root(4)(5*3^9))/108 = (root(4)(5*3^4 * 3^4 * 3))/108 =(3*3root(4)(5*3))/108 = (9root(4)(15))/(9*12) = (cancel9root(4)(15))/(cancel9*12)
This is as simplified as it gets,
(root(4)15)/12