If it is a math problem, it should be son: mother: daughter 4/7: 2/7: 1/7, which means 4: 2: 1.

Very easy to understand. Sons are twice as many as mothers (4 is twice as many as 2), and mothers are twice as many as daughters (2 is twice as many as 1). 4+2+ 1=7, that is, divide a * * * into seven parts.

If it is human nature, if only everyone had one, it would not take so much effort.