Two routes connect an origin$-$destination pair with performance functions: $t_1=5+0\mathrm{.}5(\frac{x_1}{2}{)}^2$

$t_2=7+(\frac{x_2}{4}{)}^2($with t$\text{'}$s in minutes and $x^{\text{'}}\text{'}$s in thousands of vehicles per hour$).$ It is known that

user equilibrium, $75\%$ of the origin$-$destination demand takes route $1.$ What percentage of

user equilibrium flow in route $1$ will take route $2$ if a system$-$optimal solution were achieved

and how much total system travel time $($veh$-$hr$)$ would be saved?

$38\mathrm{.}8\%,48\mathrm{.}59$ veh$-$hr

$28\mathrm{.}8\%,38\mathrm{.}59$ veh$-$hr

$18\mathrm{.}8\%,28\mathrm{.}59$ veh$-$hr

$8\mathrm{.}8\%,18\mathrm{.}59$ veh$-$hr