How is the inheritance divided if the heirs are one son, a mother, and a wife?

If the deceased leaves behind only a mother, a wife, and a son, then the mother receives one-sixth due to the presence of a lineal descendant (inheriting offspring), and the wife receives one-eighth due to the presence of a lineal descendant. The remainder goes to the son by way of ta'sib (residuary inheritance). Thus, the estate is divided into twenty-four shares: the mother receives four shares, the wife receives three shares, and the son receives seventeen shares.