Darn Dirhem Division Dilemma
A dirhem and a half is to be divided equally among one person and a certain number of other persons, so that the share of the one person is twice as many dirhems as there are other persons. How many other persons are there?
Source: al-Khwarizmi's The Condensed Book on the Calculation of al-Jabr and al-Muqabala, ca. 820