$Y-$ axis divides the line segment joining $A(-3, -4)$ and $B(1, -2)$ from $A$ in the ratio............

$ABCD$ is a parallelogram with vertices $A(x_{1}, y_{1})$,$B(x_{2}, y_{2})$,and $C(x_{3}, y_{3})$. Find the coordinates of the fourth vertex $D$ in terms of $x_{1}, x_{2}, x_{3}, y_{1}, y_{2}$,and $y_{3}$.

If $D\left(\frac{-1}{2}, \frac{5}{2}\right)$,$E(7, 3)$,and $F\left(\frac{7}{2}, \frac{7}{2}\right)$ are the midpoints of the sides of $\triangle ABC$,find the area of $\triangle ABC$.

If the distance between the points $(a, 1)$ and $(8, a)$ is $5,$ then $a=$

If the distance between $A(-4, -3)$ and $B(6, a)$ is $10$,then $a = \ldots \ldots \ldots . . .$

If one vertex of a triangle is $(1, 1)$ and the midpoints of the sides through this vertex are $(-1, 2)$ and $(3, 2)$,then find the centroid of the triangle.