Final answer:
The percent of markup charged for shipping is 12.5%.
Step-by-step explanation:
To find the percent of markup charged for shipping, we need to calculate the difference between the total cost with shipping and the cost of the book alone. In this case, the book alone cost $24 and the total with shipping was $27, so the markup for shipping is $27 - $24 = $3.
To find the percentage of markup, we divide the markup amount by the cost of the book alone and multiply by 100. In this case, the percentage of markup for shipping is ($3 / $24) * 100 = 12.5%.