Answer:  The discount is $3.60 
Explanation:
Hi, to answer this question we have to multiply the price of the baseball cap (17.99) by the discount percentage in decimal form (0.2) 
Mathematically speaking: 
17.99 x (20/100) =17.99 x 0.2= 3.598 = $3.60 
The value of the discount is $3.60 
Feel free to ask for more if needed or if you did not understand something.