Firstly, we will need to calculate the slope of the line formed by joining the coordinates.
The slope of that line would be : m = (y2 - y1)/(x2 - x1)
= (5 - 1)/(4 - 2) = 4/2 = 2
The slope of the line joining the coordinates is 2. Since the other line is parallel to this, it simply means the slope of the second line is 2. This is because of two lines are parallel, they will have the same slope.
