Three particles lie in the xy plane: 1.5 kg at (2, 1) m, 2.5 kg at (-1, 3) m and 4.0 kg at (3, -2)…

Step 1. $x$. $\sum m_ix_i = 1.5\ \text{kg} \times 2\ \text{m} + 2.5\ \text{kg} \times (-1\ \text{m}) + 4.0\ \text{kg} \times 3\ \text{m} = 12.5\ \text{kg m}$, so $x_{cm} = \dfrac{12.5\ \text{kg m}}{8.0\ \text{kg}} = 1.5625\ \text{m}$.

Step 2. $y$. $\sum m_iy_i = 1.5\ \text{kg} \times 1\ \text{m} + 2.5\ \text{kg} \times 3\ \text{m} + 4.0\ \text{kg} \times (-2\ \text{m}) = 1.0\ \text{kg m}$, so $y_{cm} = \dfrac{1.0\ \text{kg m}}{8.0\ \text{kg}} = 0.125\ \text{m}$.