It’s not a function because the line folds over itself
        
             
        
        
        
2,700 / 12 = 225
225 / 5 = 45
They can make 45 necklaces.
        
             
        
        
        
Equation for slope=1/3 and y-intercept=-1 is:
y = mx + b
where m is slope and b is y-intercept.
So, equation becomes
y = -1x + 1/3
Now put different values of x in the equation to get corresponding value of y. 
x          y
0         1/3
1        -2/3
2        -5/3
3        -8/3
-1       4/3
-2       7/3
-3       10/3
 
        
        
        
Im so sorry but I don't know this answer
        
             
        
        
        
6(2)+3y=15
12+3y=15
-12        -12
3y=3
3y/3  3/3
y=1
6(5)+3y=15
30+3y=15
-30        -30
3y=-15
3y/3   -15/3
y= -5