In an $AP$,if $d = -4$,$n = 7$,and $a_{n} = 4$,then $a$ is

How many terms of the $A.P.$ $5, 8, 11, \dots$ add up to $670$?

The first term of a finite $A.P.$ is $5$ and its last term is $95$. If the common difference of the $A.P.$ is $5$,then there are $\ldots \ldots \ldots$ terms in the $A.P.$

The $26^{\text{th}}$,$11^{\text{th}}$,and the last term of an $AP$ are $0$,$3$,and $-\frac{1}{5}$,respectively. Find the common difference and the number of terms.

The $10^{th}$ and $20^{th}$ terms of an $A.P.$ are $73$ and $143$ respectively. Find the first term,the common difference,and the $30^{th}$ term of the $A.P.$

Find the sum of the multiples of $3$ lying between $250$ and $1000$.