SOLUTION: each of mary's daughters has the same number of brothers as sisters, but each son has three times as many sisters as brother. how many children does mary have? daughters? sons?

Question 79683: each of mary's daughters has the same number of brothers as sisters, but each son has three times as many sisters as brother. how many children does mary have? daughters? sons?

Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
each of mary's daughters has the same number of brothers as sisters, but each son has three times as many sisters as brother. how many children does mary have? daughters? sons?
:
Just thinking about it, it's apparent that it would have to be 3 daughters & 2 sons. daughter has 2 sisters & 2 brothers, son has 1 brother & 3 sisters'
:
Using algebra, I came up with this:
Let d = number of daughters, s = number of sons
:
daughter> (d-1) = s; (sisters = brothers)
son>>>>>> (s-1) = 1/3d (No. of brothers 1/3 no. of sisters)
:
Arrange equation for elimination:
>>>>>>d - s = +1
-(1/3)d + s = +1
---------------------adding eliminates b:
+(2/3)d + 0 = 2
d = 2/(2/3)
d = 3 daughters
:
Find using no of sons: d - s = 1
3 - s = 1
-s = 1 - 3
-s = -2
s = 2 sons.
:
Hope this made sense

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