SOLUTION: A boy said I have as many brothers as i have sisters.Then his sister said i have double the number of brothers as i have sistes.Find the number of brothers and sisters.

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Question 395635: A boy said I have as many brothers as i have sisters.Then his sister said i have double the number of brothers as i have sistes.Find the number of brothers and sisters.
Found 2 solutions by jrfrunner, richard1234:
Answer by jrfrunner(365) (Show Source):
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let B=total boys, G=total girls
boy's criteria: equal number of brothers and sisters
girl's criteria: twice as many brothers as sisters
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if B=1 and G=1, this does not satify the conditions
if B=2 and G=1 satisfies boy's criteria but not sister's
if B=2 and G=2 does not satify the boy's criteria but satisfies sister's
if B=3 and G=2 satisfies boy's criteria but not sister's
if B=3 and G=3 niether condition satisfied
if B=4 and G=2 neither condition satisfied
if B=4 and G=3 satisfies both conditions

Answer by richard1234(7193) (Show Source):
You can put this solution on YOUR website!
The boy says that he has x brothers and x sisters, so there are x+1 boys and x girls. The sister says that she has 2y brothers and y sisters, so 2y boys and y+1 girls. These numbers differ by 1, so

2y = x+1
y+1 = x

Solving, we get y = 2, so there are 3 girls and 4 boys.