Answer:
24, most likely.
Step-by-step explanation:
I'm not completely sure if it's correct, but I think the cake equals 8, the confetti thing equals 7, and the cupcake equals 3. 
 
        
                    
             
        
        
        
I. 1250 + 20x = the cost of the party, x = the number of people attending.
II. If there are 300 people attending, the cost would be $7,250.
III. (attached) I'm not sure what kind of graph you're looking for, but I created a table. A represents the number of people attending. B represents the total cost.
IV. Daryl is incorrect. If there are 750 people attending, the total cost would be $16,250 because 750 multiplied by $20 (the cost per person) is $15,000. That plus $1,250 (the cost of the mansion) equals $16,250.
$16,250 does not equal $16,500.
 
        
             
        
        
        
For this function we can find y-intercept.
x=0, y=-2
This graph is on the top, right.