Question: How many miles of highways are in the city where the Yongle emperor greeted the person to whom the edict was addressed?

Knowledge 1: Sino-Tibetan relations during the Ming dynasty
The Information Office of the State Council of the PRC preserves an edict of the Zhengtong Emperor (r. 1435–1449) addressed to the Karmapa in 1445, written after the latter's agent had brought holy relics to the Ming court. Zhengtong had the following message delivered to the Great Treasure Prince of Dharma, the Karmapa: [SEP] Knowledge 2: Sino-Tibetan relations during the Ming dynasty
During his travels beginning in 1403, Deshin Shekpa was induced by further exhortations by the Ming court to visit Nanjing by April 10, 1407. Norbu writes that the Yongle Emperor, following the tradition of Mongol emperors and their reverence for the Sakya lamas, showed an enormous amount of deference towards Deshin Shekpa. The Yongle Emperor came out of the palace in Nanjing to greet the Karmapa and did not require him to kowtow like a tributary vassal. According to Karma Thinley, the emperor gave the Karmapa the place of honor at his left, and on a higher throne than his own. Rossabi and others describe a similar arrangement made by Kublai Khan and the Sakya Phagpa lama, writing that Kublai would "sit on a lower platform than the Tibetan cleric" when receiving religious instructions from him. [SEP] Knowledge 3: Nanjing
Express highways such as Hu–Ning, Ning–He, Ning–Hang enable commuters to travel to Shanghai, Hefei, Hangzhou, and other important cities quickly and conveniently. Inside the city of Nanjing, there are 230 km (140 mi) of highways, with a highway coverage density of 3.38 kilometres per hundred square kilometrs (5.44 mi/100 sq mi). The total road coverage density of the city is 112.56 kilometres per hundred square kilometres (181.15 mi/100 sq mi). The two artery roads in Nanjing are Zhongshan Road and Hanzhong. The two roads cross in the city centre, Xinjiekou.
Knowledge 1: Sino-Tibetan relations during the Ming dynasty
The Information Office of the State Council of the PRC preserves an edict of the Zhengtong Emperor (r. 1435–1449) addressed to the Karmapa in 1445, written after the latter's agent had brought holy relics to the Ming court. Zhengtong had the following message delivered to the Great Treasure Prince of Dharma, the Karmapa: [SEP] Knowledge 2: Sino-Tibetan relations during the Ming dynasty
In order to seek out the Karmapa, the Yongle Emperor dispatched his eunuch Hou Xian and the Buddhist monk Zhi Guang (d. 1435) to Tibet. Traveling to Lhasa either through Qinghai or via the Silk Road to Khotan, Hou Xian and Zhi Guang did not return to Nanjing until 1407. [SEP] Knowledge 3: Nanjing
Express highways such as Hu–Ning, Ning–He, Ning–Hang enable commuters to travel to Shanghai, Hefei, Hangzhou, and other important cities quickly and conveniently. Inside the city of Nanjing, there are 230 km (140 mi) of highways, with a highway coverage density of 3.38 kilometres per hundred square kilometrs (5.44 mi/100 sq mi). The total road coverage density of the city is 112.56 kilometres per hundred square kilometres (181.15 mi/100 sq mi). The two artery roads in Nanjing are Zhongshan Road and Hanzhong. The two roads cross in the city centre, Xinjiekou.
Knowledge 1: Nanjing
A monument to the huge human cost of some of the gigantic construction projects of the early Ming dynasty is the Yangshan Quarry (located some 15–20 km (9–12 mi) east of the walled city and Ming Xiaoling mausoleum), where a gigantic stele, cut on the orders of the Yongle Emperor, lies abandoned, just as it was left 600 years ago when it was understood it was impossible to move or complete it. [SEP] Knowledge 2: Sino-Tibetan relations during the Ming dynasty
During his travels beginning in 1403, Deshin Shekpa was induced by further exhortations by the Ming court to visit Nanjing by April 10, 1407. Norbu writes that the Yongle Emperor, following the tradition of Mongol emperors and their reverence for the Sakya lamas, showed an enormous amount of deference towards Deshin Shekpa. The Yongle Emperor came out of the palace in Nanjing to greet the Karmapa and did not require him to kowtow like a tributary vassal. According to Karma Thinley, the emperor gave the Karmapa the place of honor at his left, and on a higher throne than his own. Rossabi and others describe a similar arrangement made by Kublai Khan and the Sakya Phagpa lama, writing that Kublai would "sit on a lower platform than the Tibetan cleric" when receiving religious instructions from him. [SEP] Knowledge 3: Nanjing
Express highways such as Hu–Ning, Ning–He, Ning–Hang enable commuters to travel to Shanghai, Hefei, Hangzhou, and other important cities quickly and conveniently. Inside the city of Nanjing, there are 230 km (140 mi) of highways, with a highway coverage density of 3.38 kilometres per hundred square kilometrs (5.44 mi/100 sq mi). The total road coverage density of the city is 112.56 kilometres per hundred square kilometres (181.15 mi/100 sq mi). The two artery roads in Nanjing are Zhongshan Road and Hanzhong. The two roads cross in the city centre, Xinjiekou.

Answer: 140 mi