can someone help me with simplification: �ã20/5 - 1/�ã5

my first answer is 1/�ã5
my second answer is 10 -�ã5/5
but the answere I have to choose from are:
(a) �ã20 - 5�ã5/�ã5
(b) �ã20 - �ã5/5
(c) cannot be simplified
(d) 1/5�ã5
which is correct and if I'm not where did I go wrong?

�√20/5 - 1/�√5

= 2√5/5 - 1/√5*(√5/√5)
= 2√5/5 - √5/5
= √5/5

by the way:

1/√5 = √5/5 so your answer would be correct.
However, it is considered "better form" to have radicals in the denominator rationalized