Sets And Relations

Let \(\mathrm{A}=\{2,3,4\}\) and \(\mathrm{B}=\{8,9,12\}\). Then the number of elements in the relation

\(\mathrm{R}=\left\{\left(\left(a_{1}, \mathrm{~b}_{1}\right),\left(a_{2}, \mathrm{~b}_{2}\right)\right) \in(A \times B, A \times B): a_{1}\right.\) divides \(\mathrm{b}_{2}\) and \(\mathrm{a}_{2}\) divides \(\left.\mathrm{b}_{1}\right\}\) is :