Sisters and Brothers
Algebra
Level
2
My daughter has many sisters. She has as many sisters as she has brothers. Each of her brothers has twice as many sisters as brothers. How many sons and daughters do I have?
2 daughters 6 sons.
6 daughters 2 sons.
3 daughters 4 sons.
5 sons 3 daughters.
4 daughters 3 sons.
3 sons 5 daughters.
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Let one girl has n brothers. Then she has n sisters. So there are n+1 girls in all. A boy has n-1 brothers. So he has 2(n-1) sisters. Therefore n+1=2(n-1) or n=3. Therefore there are 3 boys and (3+1) or 4 girls.