How are bequests calculated when they are defined as a fixed sum plus a fraction of another bequest?

Primary text

When bequests are defined by addition (e.g., Ten plus a half of the maternal uncle's bequest), the total divisible base is found by multiplying the denominators of the fractional additions and subtracting one. The bequest for the first party (the uncle, receiving Ten plus half of the other's) is found by adding one to the addition's denominator (the half becomes two), multiplying this by the other addition's denominator (the third becomes three), multiplying that by the fixed sum (Ten), and dividing by the total divisible base. A similar method applies to the second party.