Let's calculate the markup prices for each item:

1. $22 shirt marked up 15%:

• Markup amount = 15% of $22 = $22 \times \frac{15}{100} = 3.30$
• Marked-up price = $22 + $3.30 = $25.30

2. $18 hat marked up 20%:

• Markup amount = 20% of $18 = $18 \times \frac{20}{100} = 3.60$
• Marked-up price = $18 + $3.60 = $21.60

3. $24 skirt marked up 5%:

• Markup amount = 5% of $24 = $24 \times \frac{5}{100} = 1.20$
• Marked-up price = $24 + $1.20 = $25.20

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4b. Difference between marked-up price and original price of the shirt:

• Marked-up price of the shirt = $25.30
• Original price = $22.00
• Difference = $25.30 - $22 = $3.30

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Let me know if you have any questions or want further details!

Here are five related questions to expand on this:

1. How would you calculate the markup price for a $30 jacket marked up 10%?
2. What is the markup percentage if a $20 item is marked up to $26?
3. How would you find the total profit made from selling 10 shirts marked up 15%?
4. How does the markup percentage affect customer demand in a boutique setting?
5. If an item is marked up twice, once by 10% and then by 5%, how do you calculate the final price?

Tip: When calculating percentages, breaking them into decimal form simplifies the process (e.g., 15% becomes 0.15).