Let a pair of fair dice be tossed. If the sum is 6, find the probability that one of the dice is a 2

n(S)=(6)^2=36
S={(1,1),(1,2),(1,3),(1,4),(1,5),(1,6),(2,1),(2,2),(2,3),(2,4),(2,5),(2,6),(3,1),(3,2),(3,3),(3,4),(3,5),(3,6),(4,1),(4,2),(4,3),(4,4),(4,5),(4,6),(5,1),(5,2),(5,3),(5,4),(5,5),(5,6),(6,1),(6,2),(6,3),(6,4),(6,5),(6,6)}
B={sum is 6}={(1,5),(2,4),(3,3),(4,2),(5,1)}
Let A={2 appears on at least one die}
It is require to find P(A│B)
A∩B={(2,4),(4,2)}
Then P(A│B)=(P(A∩B))/(P(B))=2/5