How are bequests calculated when two parties have bequests defined as a fixed sum plus a fraction of the other's bequest?
General Chapter
Al-Mughni
Book of Bequests
Primary text
If two parties receive a fixed sum plus a fraction of the other's bequest, the total divisible base is obtained by multiplying the denominators of the fractional additions and subtracting one. The first bequest is determined by adding one to the addition's denominator, multiplying that by the other addition's denominator, multiplying the result by the fixed sum (Ten), and dividing by the total divisible base. The second bequest is determined by adding one to the second addition's denominator, multiplying by the first addition's denominator, multiplying by Ten, and dividing by the base.
Supporting text
After establishing the first bequest, the surplus over the fixed sum (Ten) for that bequest can be multiplied by a specific factor (derived from the fractional relationship) to find the surplus for the second bequest.