Let $S=\left\{4,6,9\right\}$ and $T=\left\{9,10,11,\dots ,1000\right\}$. If
$A=\left\{a_1+a_2+\dots +a_k:k\in N,a_1,a_2,a_3,\dots ,a_k\in S\right\}$ then the sum of all the elements in the set $T-A$ is equal to _______.

The minimum number of elements that must be added to relation $R=\left\{\left(a,b\right),\left(b,c\right),\left(b,d\right)\right\}$ on the set $\left\{a,b,c,d\right\}$, so that it is an equivalence relation is

The minimum number of elements that must be added to the relation $R=(a,b),(b,\mathrm{c})$ on the set $\{\mathrm{a},\mathrm{b},\mathrm{c}\}$ so that it becomes symmetric and transitive is: