For the finite $A.P.$ $5, 9, 13, \ldots, 101$,find the $9^{th}$ term from the end.

For the $A.P.$ formed by positive multiples of $4$,$d = \ldots \ldots \ldots \ldots .$

The $10^{th}$ term of an $A.P.$ is $52$ and its $17^{th}$ term exceeds its $13^{th}$ term by $20$. Find the $A.P.$ and also its $30^{th}$ term.

Find four numbers in $A.P.$ such that their sum is $36$ and the product of means ($2^{nd}$ and $3^{rd}$ term) exceeds the product of extremes ($1^{st}$ and $4^{th}$ term) by $32.$

The $n^{th}$ term of an $A.P.$ is given by $T_{n} = 10 - 6n$. Find the sum of the first $n$ terms of the $A.P.$

Find the sum of the series: $3 + 7 + 11 + \ldots + 119$.