Workkeys Math Practice Test - Prep, Practice Exam & Study Guide

To determine how much you pay for the book after applying a 10% discount, you start by calculating the amount of the discount. The book costs $30, and a 10% discount means you multiply the cost by 0.10:

\[

30 \times 0.10 = 3

\]

This means you receive a discount of $3. To find out the final price you pay, you subtract this discount from the original price of the book:

\[

30 - 3 = 27

\]

Thus, after the discount, the amount you pay is $27. This calculation shows how to accurately apply a percentage discount to an original price, making it clear that the correct answer is indeed $27.