Challenge Answer 79

The children of the couple Aguiar

Consider "M" the number of women and "H" the number of men.

If each daughter has the same number of brothers and sisters, we have:

M-1 = H

And if each child has twice as many sisters as brothers, we have:

M = 2 (H-1) => M = 2H-2

Substituting the value of H in the second equation:

M = 2 (M-1) -2
M = 2M-2-2
M = 4

So just replace the value of M in the first equation to find H:

M-1 = H
4-1 = H
H = 3

Answer: The couple has 4 daughters and 3 sons.

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