Answer
\begin{align*} &2\text{ CuO}(s)+\text{C}(s)\rightarrow 2\text{ Cu}(s)+\text{CO}_2 (g)\\ & \text{SnO}_2(s)+\text{C}(s)\rightarrow \text{Sn}(s)+\text{CO}_2(g)\\ & 2\text{ Fe}_2\text{O}_3(s)+3\text{ C}(s)\rightarrow 4\text{ Fe}(s)+3\text{ CO}_2(g)\end{align*}
Work Step by Step
In order to balance the equation, change the coefficients in front of each molecule/atom until there are an equal number of each type of atom on each side of the equation.
