We have the segment BC, M is the midpoint
M (4,5)=(xm,ym)
B(0.9) =(x1,y1)
C(x,y)=(x2,y2)
We have the next formula
![xm=(x1+x2)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/e9e733z1iq48u13pq03ffejqsd95ii7ra9.png)
xm=4
x1=0
x2=x
we substitute the values
![4=(0+x)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/zk3jpykrlkdslgjn2jn12dmbkmcc6qnhuc.png)
we isolate x
![\begin{gathered} x=4(2) \\ x=8 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/r5s45pccjjw7zjsnd3p46uq7nqxofiyh07.png)
the for the coordinate y
![ym=(y1+y2)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/554a9veha6y9zwi1y847y23q37yt4qtoce.png)
we have
ym=5
y1=9
y2=y
we substitute the values
![\begin{gathered} 5=(9+y)/(2) \\ 10=9+y \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/engup14rrv184ytiywsruk4xyrupreaqqf.png)
then we isolate the y
![\begin{gathered} y=10-9 \\ y=1 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/e8rokhzo4cbpse8530xonnhthtnqkmrnsb.png)
the coordinate of C is (8,1)