Answer: There is decreased by 
 points in stock after three days and negative integer is used to represent.
 points in stock after three days and negative integer is used to represent.
Explanation:
Since we have given that 
Point decreased by on Monday = 

Point decreased by on Tuesday = 

Point decreased by on Wednesday = 

So, total decreased in these three days are 

hence, there is decreased by 
 points in stock after three days and negative integer is used to represent.
 points in stock after three days and negative integer is used to represent.