Simplify by adding. \( \begin{array}{lll}\text { a) } x+\frac{1}{2} x & \text { b) } \frac{3 m}{7}+\frac{2 m}{7} & \text { c) } \frac{n^{2}}{4}+\frac{2 n^{2}}{3} \\ \text { Subtract these monomials: } & \end{array} \)

To simplify the expressions by adding: a) \( x + \frac{1}{2} x = \frac{2}{2}x + \frac{1}{2}x = \frac{3}{2}x \) b) \( \frac{3 m}{7} + \frac{2 m}{7} = \frac{5 m}{7} \) c) To add \( \frac{n^{2}}{4}+\frac{2 n^{2}}{3} \), we need a common denominator, which is 12. So: \[ \frac{n^{2}}{4} = \frac{3n^{2}}{12} \quad \text{and} \quad \frac{2 n^{2}}{3} = \frac{8n^{2}}{12} \] Adding these gives: \[ \frac{3n^{2}}{12} + \frac{8n^{2}}{12} = \frac{11n^{2}}{12} \] To subtract such monomials, it mainly involves aligning like terms and ensuring a common denominator where necessary. Keep track of the signs and align the variables for a smooth operation!