Answer :
The midpoint of two endpoints is the sum of both coordinates divided by 2. Now that we have one endpoint and a midpoint, the other endpoint can be calculated as follows;
A(6, 4), B(x2, y2), Midpoint (4, 8)
[tex]\begin{gathered} \text{Midpoint}=\frac{(x2+x1)}{2} \\ 4=\frac{(x2+6)}{2} \\ 4\times2=x2+6 \\ 8-6=x2 \\ 2=x2 \\ \text{For the other endpoint (y}1) \\ \text{Midpoint}=\frac{(y2+4)}{2} \\ 8=\frac{(y2+4)}{2} \\ 8\times2=y2+4 \\ 16-4=y2 \\ 12=y2 \end{gathered}[/tex]The other endpoint is thus shown as (2, 12)