If two events, A and B, are such that $P(A) = 1/5$, $P(A \cup B) = 12/35$, and $P(A \cap B) = 1/48$, find the following probabilities:
1. $P_1 = P(B | A)$;
2. $P_2 = P(B)$;
3. $P_3 = P(A | B)$;
4. $P_4 = P(A | B^c)$.
Instructions on how to input the answer: 1) If an answer is a rational number, simplify it into reduced form and use forward slash to denote division. For example, $4/6$ is written as $2/3$; $-4/6$ is written as $-2/3$. 2) Input the string of the answers separated by a comma. Do not include any space in the text.
$(P_1, P_2, P_3, P_4) = (\_)$