Hello, the answer is x=-1/2 
Here are the steps....
<span><span><span><span><span>−<span>7x</span></span>+12</span>+</span>−<span>2x</span></span>=<span>23+<span>13x</span></span></span><span><span><span>(<span><span>−<span>7x</span></span>+<span>−<span>2x</span></span></span>)</span>+<span>(12)</span></span>=<span><span>13x</span>+23</span></span>(Combine Like Terms)<span><span><span>−<span>9x</span></span>+12</span>=<span><span>13x</span>+23</span></span><span><span><span>−<span>9x</span></span>+12</span>=<span><span>13x</span>+<span>23
</span></span></span><span><span><span><span>−<span>9x</span></span>+12</span>−<span>13x</span></span>=<span><span><span>13x</span>+23</span>−<span>13x</span></span></span><span><span><span>−<span>22x</span></span>+12</span>=<span>23
</span></span><span><span><span><span>−<span>22x</span></span>+12</span>−12</span>=<span>23−12</span></span><span><span>−<span>22x</span></span>=<span>11
</span></span><span><span>−<span>22x</span></span><span>−22</span></span>=<span><span><span>11<span>−22</span></span></span></span><span>x=<span><span><span>−1</span>2</span></span></span><span>
</span>Hope this helps you!!
        
             
        
        
        
Solve the second equation using the given choices:
Y = 3x + 6
Replacing x with the given choices and matching the y values the answer is the second choice
(0,6) and (-2,0)
 
        
             
        
        
        
Answer:
C 
Step-by-step explanation:
The domain are the values of x on a graph so you can see on both sides the x value goes on forever and only C fills that requirement 
C
 
        
             
        
        
        
Answer:
15n
Step-by-step explanation:
Since it is 15 samples per day, you just need to multiple 15 by the number of days.