Answer:
Step-by-step explanation:
Express this time interval in set notation:
15 ≤ t ≤ 20
This says that the waiting time will be between 15 and 20 minutes.
The answer is (-2, -3) since 2*-2–(+)3= -1 and 2*-2-4*-3= 8.
See the attached graph
<h2>
Explanation:</h2>
Hello! Remember to write complete questions in order to get good and exact answers. Here you don't provide any system so I couldn't help you in an exact way, but in a general manner. When solving systems by graphing we just need to find the points of intersection of the graphs of the functions that built up the system.
Suppose you have the following system of linear equation:

yBy using graphing tools, we get the graph shown below. As you can see, the point of intersection of both lines is 
<h2>Learn more:</h2>
Solving systems by graphing: brainly.com/question/13799715
#LearnWithBrainly
I think the answer could be A but I'm not so sure because at first Kayla has 6 boxes with x amount of books in the boxes with four left over so the equation would be 6x+4= number of books. So if she then replaces the now five boxes with x amount of books in them and adds four books to each of the five boxes you get 5x+4=number of books so it all equals out to the same number of books on both sides of the equal sign for 6x+4=5x+4