Final answer:
To find the number of second-hand shirts Emily owns, calculate 75% of 24, which results in 18 second-hand shirts.
Step-by-step explanation:
If 75% of Emily's shirts are second hand and she owns 24 shirts, we can find out how many of Emily's shirts are second hand by calculating 75% of 24. To do this, we convert the percentage into a decimal by dividing by 100, meaning 75% becomes 0.75.
Then, we multiply this decimal by the total number of shirts to get the number of second-hand shirts.
Calculation: 0.75 (as a decimal) × 24 (total number of shirts) = 18 (second-hand shirts).
So, Emily has 18 second-hand shirts.