Three particles of masses $1 \mathrm{~kg}, \frac{3}{2} \mathrm{~kg}$, and $2 \mathrm{~kg}$ are located at the vertices of an equilateral triangle of side $a$. The $x_{1} y$ coordinates of the centre of mass
are
(a) $\left(\frac{5 a}{9}, \frac{2 a}{3 \sqrt{3}}\right)$
(b) $\left(\frac{2 a}{3 \sqrt{3}}, \frac{5 a}{9}\right)$
(c) $\left(\frac{5 a}{9}, \frac{2 a}{\sqrt{3}}\right)$
(d) $\left(\frac{2 a}{\sqrt{3}}, \frac{5 a}{9}\right)$