Answer:
ok so it's telling you that for 10 folder it cost 1.50 cents each and for 20 it's 3.50 and 30 5$ and 40 6$ and it's basically telling you that what ever your reading you have to think how much did that person spend or bought and how much do u think each folder it's so u have to figure out how many does each cost of cents for each folder. 
 
        
             
        
        
        
5x - 6y = 30
6y = 5x - 30
Y = 5/6x - 5
y intercept = -5
Therefore (0, -5)
0 = 5/6x - 5
5/6x = 5
x = 6
x intercept = 6
therefore (6,0)
answer : first one 
x intercept =