You can put this solution on YOUR website! We have a line that is horizontal and it follows that its slope is 0. This means that a line parallel to this line also has slope 0 and is in fact a horizontal line. We will expect that this line will be of the form y = (some number). And since our coordinate is (5,1) [implying that y = 1], a good guess would be that the line is y =1. Let's solve this algebraically.
We have a slope and we have a point. Let's use point-slope form.
y - y1 = m(x-x1)
y - 1 = 0(x-5)
y - 1 = 0
y = 1 <--- Just as we expected.
You can put this solution on YOUR website! y =3 has a slope=0, which means it is a horizontal line. It contains all x from -infinity to +infinity.
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A line parallel to it will be horizontal, too.
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y = 1 will contain all x values from -infinity to +infinity, so it doubtless contains (5,1).
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