For a given $A.P.$,$a=2$ and $d=3$. Then,$S_{30} = \dots$

The sum of the first $n$ terms of an $A.P.$ is given by $S_n = 3n^2 + 5n$. Then,the $n^{th}$ term of the $A.P.$ $T_n = \ldots$

The sum of the first five terms of an $AP$ and the sum of the first seven terms of the same $AP$ is $167$. If the sum of the first ten terms of this $AP$ is $235$,find the sum of its first twenty terms.

The sum of how many terms of the $A.P.$ $54, 51, 48, \dots$ is $513$? Explain the reason for getting two different answers.

Kanika was given her pocket money on Jan $1^{\text{st}}, 2008$. She puts $Rs.\, 1$ on Day $1$,$Rs.\, 2$ on Day $2$,$Rs.\, 3$ on Day $3$,and continued doing so till the end of the month,from this money into her piggy bank. She also spent $Rs.\, 204$ of her pocket money,and found that at the end of the month she still had $Rs.\, 100$ with her. How much was her pocket money for the month? (in $Rs.$)

Which term of the $A.P. \, 53, 48, 43, \ldots$ is the first negative term?