If the $m^{\mathrm{th}}$ term of an A.P. is $n$ and the $n^{\mathrm{th}}$ term is $m,$ then its $r^{\mathrm{th}}$ term will be:

For what value of $k$, $\left[10, k, -2\right]$ are in A.P.?

If the sum of $n$ terms of an A.P. be $3n^2+n$ and its common difference is $6,$ first term is:

If the sum of $n$ terms of an A.P. is $3n^2+5n,$ then which of its terms is $164$?