15x-10=20
 +10 +10
15x=30
\15 /15
x=2
you add 10 to both -10 (they cancek eachother out) and 20 (equals 30) 
Then you divide 30 by 15 (equals 2) and 15 by 15 (they cancel eachother out) 
Then you get x=2
        
                    
             
        
        
        
Answer:
 
 
Step-by-step explanation:

 
        
             
        
        
        
Step-by-step explanation:
A)
The length of the box is 30 − 2x inches.
The width of the box is 30 − 2x inches.
The height of the box is x inches.
So the volume is:
V = x (30 − 2x)²
B)
V(3) = 3 (30 − 6)² = 1728
V(4) = 4 (30 − 8)² = 1936
V(5) = 5 (30 − 10)² = 2000
V(6) = 6 (30 − 12)² = 1944
V(7) = 7 (30 − 14)² = 1792
As x increases, the volume of the box increases to a maximum and then decreases.
C)
The ends of the domain occur when V = 0.
0 = x (30 − 2x)²
x = 0 or 15
So the domain is (0, 15).
 
        
             
        
        
        
No because when you add any 2 sides the answer has to be bigger than the 3rd side
ex: 2+7=9
9 is too small, so the tips of the side that is 2ft would not touch the side that is 7ft
        
             
        
        
        
The answers for one, two, and three are:
False
True
True