Question 168979
 It has been many years since I have had any math, so I am really strugling.
Can you explain this for me, and how to solve it, I would be very greatful. 
Does the line y=4 is a vertical line
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It's a horizontal line.  Actually, it's parallel to the x-axis, which is usually the horizontal axis.
You can see that if you graph it.  Since it's a straight line, all you need are 2 points, then draw the line thru them.
You can use (0,4) and 4,4).  You'll see that no matter what the value of x is, y is 4, so it's parallel to the x-axis.