三千餘里 Three Thousand Li And More
國王道：「寡人曾差夜不收軍馬到那裡探聽聲息，往來要行五十餘日。坐落南方，約有三千餘里。」行者聞言，叫：「八戒、沙僧護持在此，老孫去來。」国王道：「寡人曾差夜不收军马到那里探听声息，往来要行五十余日。坐落南方，约有三千余里。」行者闻言，叫：「八戒、沙僧护持在此，老孙去来。」
逐句解 Line by line
The king said: "I once sent out scouting horse to listen for word of them there. The going and the returning took above fifty days."
差 is chāi, to send somebody on an official errand, not the chà of falling short. 夜不收 was the Ming army's word for scouts, and the three characters read literally as not-coming-back-at-night, which is a fair description of the duty. The book leaves the term in the king's mouth without explaining it, which is itself a way of placing him.
"It lies to the south, something over three thousand li."
里 stays as li. It is a unit rather than a word, and putting it into miles would hand the sentence a precision the original does not claim — the figure already comes with an about attached. 坐落 is the standing verb for where a place sits.
Hearing this, Pilgrim called out: "Bajie, Sha Monk — keep guard here. Old Sun is off and back."
去來 is a single word in colloquial usage, covering the whole round trip, so the departure is announced as though already returned from. Fifty days of scouting have just been reported to him and he answers them with two characters.
The king answers with the only measurement his court has, and it measures effort rather than distance: fifty days there and back. The three thousand li come second and roughly; the direction comes first of all. This is how a kingdom that cannot reach a place describes where it is.
Wukong's reply does not engage with the fifty days at all. He gives his two brothers their orders and closes with a word that treats going and returning as one action. Nothing in the sentence concedes that a distance has just been named.