SOLUTION: How many children are there in a family where,in each girl has as many brothers as sisters,but each boy has twice as many sisters as brothers?

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Question 1127974: How many children are there in a family where,in each girl has as many brothers as sisters,but each boy has twice as many sisters as brothers?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = the number of girls
Let +b+ = the number of boys
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(1) +a+-+1+=+b+
(2) +2%2A%28+b+-+1+%29+=+a+
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Note that when I am counting a girls sisters,
I count them as +a+-+1+
When counting a boys brother's, I count them as
+b+-+1+
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Plug (1) into (2)
(2) +2%2A%28+a+-+1+-+1+%29+=+a+
(2) +2a+-+4+=+a+
(2) +a+=+4+
and
(1) +a+-+1+=+b+
(1) +4+-+1+=+b+
(1) +b+=+3+
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There are 4 girls and 3 boys
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check:
Each girl has as many sisters as brothers TRUE
Each boy has twice as many sisters as brothers TRUE