Let $R$ be a relation defined on the set $\{1,2,3,4\times\{1,2,3,4\}$ by \[ R=\{((a,b),(c,d)) : 2a+3b=3c+4d\} \] Then the number of elements in $R$ is
If a random variable \( x \) has the probability distribution 
then \( P(3<x \leq 6) \) is equal to