Complex sentence: The foundation is the sole beneficiary of the Alfred I. duPont Testamentary Trust, which du Pont's will stipulated that the trust make an annual disbursement of an amount equal to 3% of the trust's value.
Split into simpler sentences: The foundation is the sole beneficiary of the Alfred I. duPont Testamentary Trust. Alfred du Pont's will stipulated that the trust would make an annual disbursement of an amount equal to 3% of the trust's value.