Xm=(2+2)/2=2
Ym=(1+4)/2=2.5
(2,2.5)
        
             
        
        
        
Answer:
$10
Step-by-step explanation
Liam has $10 left for himself. Simply divide $240 by the 24 kids and you get $10 as your total. Thsi is what I could get as the answer since the price of the gift was'nt included.
 
        
             
        
        
        
The answer for your questions is -5
        
             
        
        
        

This happens whenever 

 or 

. More generally, 

 whenever you start with one of these angles and add any multiple of 

, so the general solution would be 

, where 

 is any integer. (Notice that when 

, you end up with 

.)