Answer:
12.5%
Explanation:
Given parameters: 
Cost price = 32000
Selling price of the AC = 28000
Unknown 
Arthur's loss percent = ? 
Solution: 
To find the loss percent; use the formula below;
 Arthur's loss percent = 

Input the parameters and solve; 
 Arthur's loss percent = 
 x 100 = 12.5%
 x 100 = 12.5%
His loss percentage is 12.5%