MathematicsHard58×since 2004Q5362Let R be a relation from the set {1,2,3,…,60}\{1,2,3, \ldots, 60\}{1,2,3,…,60} to itself such that R={(a,b):b=pqR=\{(a, b): b=p qR={(a,b):b=pq, where p,q⩾3p, q \geqslant 3p,q⩾3 are prime numbers}. Then, the number of elements in R is :A600B660C540D720Check answerSkip