Tom had bought some pens. Tom would have 225 more pens if he had 15% more. Sally had some pens too. Tom has 50% fewer pens than sally. How many pens does sally have?

To solve the problem, we need to determine how many pens Sally has, given the information about Tom's pens. Let's break it down step by step.

### Step 1: Determine Tom's Current Number of Pens

Let \( x \) be the number of pens Tom currently has.

According to the problem, if Tom had 15% more pens, he would have 225 more pens. We can express this situation with the following equation:

\[
x + 0.15x = x + 225
\]

Simplifying the left side of the equation, we get:

\[
1.15x = x + 225
\]

Subtract \( x \) from both sides:

\[
0.15x = 225
\]

Solve for \( x \) by dividing both sides by 0.15:

\[
x = \frac{225}{0.15} = 1500
\]

So, Tom currently has 1500 pens.

### Step 2: Determine Sally's Number of Pens

We are given that Tom has 50% fewer pens than Sally. This means that Tom has half as many pens as Sally. If \( y \) represents the number of pens Sally has, then:

\[
x = 0.5y
\]

We already know \( x = 1500 \), so we can substitute:

\[
1500 = 0.5y
\]

Solve for \( y \) by dividing both sides by 0.5:

\[
y = \frac{1500}{0.5} = 3000
\]

Therefore, Sally has 3000 pens.

### Conclusion

Sally has **3000 pens**.

If you have any further questions or need additional explanations, feel free to ask!

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Here are some related questions for further exploration:

1. How many pens would Sally have if she had 20% more pens?
2. If Tom gave 200 pens to Sally, how many pens would each have?
3. What percentage of Sally's pens does Tom have?
4. If Sally had 30% fewer pens, how many would she have?
5. How many pens do they have in total?
6. If both Tom and Sally increased their pens by 10%, how many more pens would they have together?
7. What is the ratio of Tom's pens to Sally's pens?
8. How many more pens would Tom need to have the same amount as Sally?

**Tip:** When dealing with percentages, remember that an increase of \( n\% \) can be expressed as multiplying the original amount by \( 1 + \frac{n}{100} \). Similarly, a decrease of \( n\% \) can be expressed as multiplying by \( 1 - \frac{n}{100} \).

Learn how to solve a problem involving Tom and Sally's pens using percentages and ratios. Find out how many pens Sally has based on given information about Tom's pens. Suitable for Grades 6-8.

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