Let’s consider A$(-2,-1)$,B$(1,0)$,C$(4,3)$ and D$(1,2)$ are the given points.
Let’s take P(x, y) be the point of intersection of the diagonals of the parallelogram formed by the given points.
As We know that, diagonals of a parallelogram bisect each other. Therefore,
$x=\frac{2+4}{2}$
$\Rightarrow x=\frac{2}{2}=1$
$y=\frac{-1+3}{2}=\frac{2}{2}=1$
Hence, the coordinates of P are $(1,1)$