Logic Puzzle

I need to figure out how many sisters Sally has.

Let me break this down step by step:

• Sally has 3 brothers
• Each brother has 2 sisters

Since Sally is one of the girls in the family, and each brother has 2 sisters, this means there are 2 sisters total that the brothers count.

One of those sisters is Sally herself, so there must be 1 additional sister.

Therefore, Sally has 1 sister.

To verify: Sally + 1 sister = 2 sisters total, and each of the 3 brothers correctly has 2 sisters (Sally and her sister).