Now given a that a guest on horseback rides 300 li in a day. The guest leaves his clothes behind. The host discovers them after 1/3 day, and he starts out with the clothes. As soon as he catches up with the guest, the host gives back the clothes and returns home in 3/4 day. Assume the host rides without a stop. Tell how far can he go in a day?
Jiuzhang Suanshu (The Nine Chapters on the Mathematical Art), c. 100 BCE
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The answer is: 780 li
"Beyond the Call of Duty," Convergence (September 2008)