Question 515475
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?
:
Let d = no. of daughters
Let s = no. of sons
:
"She has as many sisters as she has brothers", therefore:
s = d - 1
:
"Each of her brothers has twice as many sisters as brothers."
d = 2(s-1)
d = 2s - 2
replace s with (d-1)
d = 2(d-1) - 2
d = 2d - 2 - 2
d - 2d = -4
-d = -4
d = 4 daughters
then
4 - 1 = 3 sons