m_{3} = \frac{200 g \cdot 10 cm - 50 g \cdot 10 cm}{10 cm} = \underline{\underline{100 g}}

${m_3 = \frac{200\, \text{g} \cdot 10\, \text{cm} - 50 \text{g}\cdot 10\, \text{cm}}{10\, \text{cm} }= \underline{\underline{100\, \text{g}}}}$

Error