Among the relations $S=\left\{(a, b): a, b \in R -\{0\}, 2+\frac{a}{b}>\right\}$ and $T=\left\{(a, b): a, b \in R , a^2-b^2 \in Z\right\}$,
Let \( A = \{1, 2, 3, 4, 5, 6, 7\} \). Then the relation \( R = \{(x, y) \in A \times A : x + y = 7\} \) is: