Exercise

The first term of the A.P. is $12$. The number of terms is $15$ and their sum is $390$. The common difference is

The sum of $10$ terms of the A.P. $2,$ $7,$ $12,\dots$ is

The first and last terms of an A.P. are $1$ and $11$. If the sum of its terms is $36,$ then the number of terms is

The $n^{th}$ term of $3,7,11,15,......$ is

Ratio of the sum of $n$ terms of A.P's are $(3n+8):(7n+15)$, then the ratio of their $5^{\mathrm{th}}$ terms is

If the last term of an A.P. is $119$ and the $8^{\mathrm{th}}$ term from the end is $91$ then the common difference of the A.P. is

Find the ${10}^{\mathrm{th}}$ term from the end of the A.P. $4, 9, 14, ..., 254$?

Write the first four terms of the following sequence whose $n^{th}$ term is:

$n^2-16$