(b) : $R = \{(a,b):b = pq$, where $p,q \geq 3$ are prime numbers\}\\ Number of possible values of $a = 60$\\ For $b = pq$, if $p = 3,q = 3,5,7,11,13,17,19$\\ If $p = 5,q = 5,7,11$; if $p = 7,q = 7$\\ $\therefore\$ Number of elements in $R = 60(7 + 3 + 1) = 660$