Let the sum of the first n terms of a non-constant A.P., a_1, a_2, a_3, … … … be 50 n +(n ( n -7))/2 A, where A is a constant. If d is the common…

Let the sum of the first $\displaystyle n$ terms of a non-constant A.P., $\displaystyle \mathrm{a}_1, \mathrm{a}_2, \mathrm{a}_3, \ldots \ldots \ldots$ be $\displaystyle 50 \mathrm{n}+\frac{\mathrm{n}(\mathrm{n}-7)}{2} \mathrm{~A}$, where A is a constant. If d is the common difference of this A.P., then the ordered pair $\displaystyle \left(\mathrm{d}, \mathrm{a}_{50}\right)$ is equal to :