If $2$ moles of an ideal monoatomic gas at tempterature $5T_0$ is mixed with $3$ moles of another ideal monoatomic gas at temperature $3T_0$, what will be the temperature of the mixture?

Question

$\begin{array}{1 1} 1.9\;T_0 \\ 3.9\;T_0 \\ 3.8\;T_0 \\ 4.2\;T_0 \end{array}$