Answer: 20%.
Step-by-step explanation:
Given, The price of a shirt is marked down from $12.50 to $10.00.
Previous price = $12.50
New price = $10.00
Change in price = Previous price - New price
= $12.50 - $10.00
= $2.50
Now, the percent decrease of the shirt = [tex]\dfrac{\text{Change in price}}{\text{Prevoius price}}\times100[/tex]
[tex]=\dfrac{2.50}{12.50}\times100\\\\=20\%[/tex]
Hence, the percent decrease of the shirt = 20%.