First you must acknowledge that you are dealing with a line therefore you must write linear equation or linear function in this case.
Linear function has a form of,
Then calculate the slope <em>m</em> using the coordinates of two points. Let say <em>A(x1, y1)</em> and <em>B(x2, y2)</em>,
Now pick a point either <em>A</em> or <em>B</em> and insert coordinates of either one of them in the linear equation also insert the slope you just calculated, I will pick point <em>A</em>.
From here you solve the equation for n,
So you have slope <em>m</em> and variable <em>n</em> therefore you can write down the equation of the line,
Hope this helps.
r3t40