Feeling Sluggish

A leech invited a slug for lunch a leuca away.  But he could only crawl an inch a day.  How long will it take the slug to get his meal? [a leuca = 1500 paces, a pace = 5 feet]

Propositiones ad acuendos juvenes (Problems to Sharpen the Young), Alcuin of York, c. 800 CE

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