If $a, b, c$ are in Arithmetic Progression,then $(a - c)^2 = \dots$

Let $S_{n}$ denote the sum of the first $n$ terms of an arithmetic progression. If $S_{10} = 530$ and $S_{5} = 140$,then $S_{20} - S_{6}$ is equal to:

Let $f: R \rightarrow R$ be such that for all $x \in R$,the terms $(2^{1+x}+2^{1-x})$,$f(x)$,and $(3^x+3^{-x})$ are in $A.P.$. Then the minimum value of $f(x)$ is:

If $2x, x + 8$ and $3x + 1$ are in an arithmetic progression,then $x = \dots$

Three positive numbers $a, b,$ and $c$ are in an Arithmetic Progression $(AP)$ and $abc = 4$. The minimum possible value of $b$ is:

How many multiples of $5$ are there from $10$ to $95$,including both $10$ and $95$?