7. Find the number of elements in only one set

If $P$, $Q$ and $R$ are three sets such that $P$ has 30 elements, $Q$ has 27 elements, $R$ has 29 elements, $P \cap Q$ has 18 elements, $Q \cap R$ has 15 elements, $P \cap R$ has 15 elements and $P \cap Q \cap R$ has 11 elements, then find number of elements only in set $P$, and only in set $R$?

 

1. Number of elements only in set $P$

 

2. Number of elements only in set $R$