Mathematicas
posted by Nina .
Sam and Susie are twins. Sam has as many brothers as he has sisters. Suzie has at least 1 sister, and twice as many brothers as sisters. How many kids are in the family altogether?

Here is a similar version of this popular problem which should give you some clues as to how to approach yous.
In a family of children,
1) each girl has as many bothers as sisters but
2) each boy has 3 times as many sisters as brothers.
How many children are in the family?
Let g = the number of girls
Let b = the number of boys
1Looking at the girls only, it is clear that each girl has one less as many sisters as there are girls in the first place.
2Therefore, we can write that each girl has (g  1) sisters.
3From statement #1, if each girl has as many brothers as sisters, we can write that (g  1) = b.
4Similarly, we know that each boy has (b  1) brothers and g sisters.
5From statement #2, if each boy has 3 times as many sisters as brothers, we can write that g = 3(b  1) = 3b  3.
6Substituting (5) into (3) yields 3b  3  1 = b.
7Then, 2b = 4 making b = 2 and g = 3.
Good luck. 
I think there are three children