Find the Center of Mass of the Given System of Point

Multiple Choice

Find the center of mass of the given system of point masses. $\begin{array}{|c|c|c|c|}\hline m_{i} & 9 & 4 & 7 \\\hline\left(x_{i}, y_{i}\right) & (-1,0) & (7,-3) & (1,-9) \\\hline\end{array}$

A) $\bar { x } = \frac { 5 } { 4 } , \bar { y } = - \frac { 19 } { 5 }$
B) $\bar { x } = \frac { 13 } { 10 } , \bar { y } = - \frac { 15 } { 4 }$
C) $\bar { x } = \frac { 29 } { 23 } , \bar { y } = - \frac { 72 } { 23 }$
D) $\bar { x } = \frac { 29 } { 20 } , \bar { y } = - \frac { 18 } { 5 }$
E) $\bar { x } = \frac { 7 } { 5 } , \bar { y } = - \frac { 73 } { 20 }$