Travelers arrive at one security check point at Portland airport and join one of the two lines. If a traveler has a valid TSA Pre status, this traveler will join the line that is served by a screener first and a dedicated X$-$ray machine. Otherwise, all the travelers will join a line that is served by the first available among $3$ screeners and $3$ X$-$ray machines. To analyze this scenario, we need to use $[$one$]$ and $[$theother$].$