Alright, let's tackle this problem step by step. The question is:

"Sally (a girl) has 3 brothers. Each brother has 2 sisters. How many sisters does Sally have?"

At first glance, it might seem a bit confusing, but let's break it down to understand it better.

Understanding the Problem

We have a family with several children, including Sally and her brothers and sisters. Here's what we know:

1. Sally is a girl.
2. Sally has 3 brothers.
3. Each brother has 2 sisters.

We need to determine how many sisters Sally has.

Identifying the Siblings

First, let's list out the siblings based on the information given.

• Sally: She is one girl in the family.
• Brothers: Sally has 3 brothers. So, there are 3 boys in the family.

Now, the next piece of information is that "each brother has 2 sisters."

This means that if you pick any one of the 3 brothers, that brother has 2 sisters.

Determining the Sisters

Here's where it might get a bit tricky. We know Sally is one sister, but are there more?

Let's think about what "each brother has 2 sisters" implies.

If a brother has 2 sisters, those sisters must include Sally and possibly another girl.

But wait—Sally is already one sister. So, if a brother has 2 sisters, and one is Sally, who is the other one?

This suggests that there must be at least one more sister besides Sally to make the count of sisters equal to 2 for each brother.

Let's test this:

• Suppose there is only Sally as the sister. Then each brother would have only 1 sister (Sally), but the problem states each has 2 sisters. So, this can't be the case.

• Therefore, there must be another sister besides Sally.

So, the sisters are:

1. Sally
2. Another girl (let's call her, say, Emily)

Now, let's check if this satisfies the condition that each brother has 2 sisters.

Each brother's sisters would be:

• Sally
• Emily

That's 2 sisters, which matches the given information.

Verifying the Number of Sisters

Now, the question is asking: How many sisters does Sally have?

We've established that the sisters in the family are:

• Sally
• Emily

But the question is about Sally's sisters, not including herself.

So, Sally's sisters are:

• Emily

That's 1 sister.

Wait a minute, but earlier we thought there are 2 sisters in total (Sally and Emily), but Sally's sisters would be just Emily, making it 1 sister.

But let's double-check the initial interpretation to ensure we didn't make a mistake.

Re-evaluating the Interpretation

The confusion might arise from how we're counting the sisters.

Total sisters in the family:

• Sally
• Emily

Total brothers: 3

Now, "each brother has 2 sisters." Each brother's sisters are Sally and Emily, which is 2. This checks out.

Now, how many sisters does Sally have?

Sally's sisters are the other girls in the family besides herself, which is Emily. So, Sally has 1 sister.

But let me think if there could be more sisters.

Suppose there are 3 sisters: Sally, Emily, and another girl (let's say, Anna).

Then each brother would have 3 sisters (Sally, Emily, Anna), but the problem says each has 2 sisters. So, this can't be.

Therefore, the only possibility is that there are 2 sisters in total: Sally and Emily.

Thus, Sally has 1 sister.

Potential Misinterpretation

Initially, one might think that since each brother has 2 sisters, and there are 3 brothers, there are 6 sister instances (3 brothers × 2 sisters each), leading to more sisters. But this would be incorrect because all brothers share the same sisters; the sisters aren't unique to each brother.

For example, if there are 2 sisters, each of the 3 brothers has those 2 sisters, totaling 6 sister instances (3 brothers × 2 sisters), but the actual number of sisters is just 2.

Final Confirmation

Let's confirm with the numbers:

• Sisters: Sally and Emily (total 2 girls)
• Brothers: 3 boys

Each brother's sisters: Sally and Emily (2 sisters) — matches the given information.

Sally's sisters: Emily (1 sister)

Therefore, Sally has 1 sister.

Conclusion

After carefully analyzing the problem and considering the relationships, the correct answer is:

Sally has 1 sister.