Solution: the son inherits two-thirds of the inheritance and the wife inherits one-third. So it's son 2: 1 wife

If it is a daughter, she inherits one-third and her wife inherits two-thirds. So it's wife 2: 1 daughter.

Because the mother is in the middle, the son: mother: daughter is 2: 1: 1/2.

If the wife gets X, the son gets 2x, the daughter gets 1/2x, and the total property is 1.

x+2x+ 1/2x= 1

Solution: x=2/7, then 2x=4/7, 1/2x= 1/7.