If two dice are rolled, what is the probability of rolling a sum of 6, given that doubles are not rolled?

Ways to get a sum of six

=|{(1,5),(2,4),(4,2),(5,1)}|
= 4 ways
given that doubles are not rolled, therefore (3,3) was absent.
Total number of ways:
6 faces * (6-1) faces to eliminate doubles
= 30

So probability of rolling a total of 6
= P(6)
= ?