The $A.P.$ with the first term $-3$ and the common difference $4$ is $ \ldots \ldots \ldots \ldots . $

For a given $A.P.$,$T_{7} = 12$ and $T_{12} = 72$. Then,$d = \dots \dots \dots \dots$

$A$ person has to clear a debt of $Rs. 3250$ by monthly instalments. In the first month he has to pay $Rs. 20$ and then onwards every instalment is $Rs. 15$ more than the previous instalment. How long will it take to clear the debt?

Write the first three terms of the $APs$ when $a$ and $d$ are as given below:
$a=\sqrt{2}, d=\frac{1}{\sqrt{2}}$

For the $A.P.$ $-2, -4, -6, -8, \ldots,$ the common difference is............

The sum of the first $n$ terms of an $AP$ whose first term is $8$ and the common difference is $20$ is equal to the sum of first $2n$ terms of another $AP$ whose first term is $-30$ and the common difference is $8$. Find $n$.