Given : x_1 = 1 m m_1 = 3 kg m_2 =2kg x_2 = -2 m m_3 = 1 kgPosition of centre of mass X = -1 mUsing X = \\dfrac{m_1x_1 + m_2x_2 +m_3x_3}{m_1+m_2+m_3} \ herefore -1 = \\dfrac{3\ imes 1 + 2\ imes (-2) + 1\ imes x_3}{3+2+1} \\implies x_3 = -5 m