$(3$ pts$)5,000$ vehicles will leave from origin $"$O$"$ and arrive to destination $"$D$".$ There are two alternative routes, Route $1$ and Route $2,$ for those vehicles to choose. The travel time on Route $1$ can be calculated according to the equation: $t_1=10(1+\frac{v_1}{2000}),$ where $v_1$ is the number of vehicles using Route $1.$ Similarly, the travel time on Route $2$ can be calculated as $t_2=20(1+\frac{v_2}{1000}),$ where $v_2$ is the number of vehicles using Route $2.$ How many vehicles will use Route $1$ and how many will use Route $2$ at the User Equilibrium $($UE$)$ status? What will be the travel times on Route $1$ and Route $2$ at the UE status?