with LCFS, which packet/process will be serviced first in case of out-of-order arrival: the recently arrived but stale, or the previously arrived but fresh packet? E.g. at $t = 5$, a comparatively fresh packet generated at $t=3$ is waiting in the queue when a stale packet generated at $t = 1$ arrives. As per LCFS, we always service the most recently arrived one (here the packet generated at $t=3$). However, that increases the age of the system $(5-1 = 4)$. If we had processed the $t = 5$ packet, our system would have been fresher $(5-3 = 2)$ Here the source is the same, so as long as we have the recent information, we can discard the old information.