If $^8C_r = ^8C_{r+2}$,then the value of $^rC_2$ is

From among the $36$ teachers in a school,one principal and one vice-principal are to be appointed. In how many ways can this be done?

How many numbers of five digits can be formed with the digits $0, 1, 2, 3, 5$ and $6$?

$A$ student is to answer $10$ out of $13$ questions in an examination such that he must choose at least $4$ from the first $5$ questions. The number of choices available to him is

The total number of permutations of the letters of the word "$BANANA$" is

The number of triangles that can be formed by choosing the vertices from a set of $12$ points,seven of which lie on the same straight line,is