The equation of a line is y=mx+b, or y equals m times x plus b. y is the y coordinate of one coordinate pair in the line. m is the slope of the line. I had easily learned how to spot the slope of the line by the saying " Rise over run". First you see how many grid squares it goes up, then how many it goes over. This is the "m". Now the x is an x coordinate in the same coordinate as the y. To find the "b'', you look for where the line meets the y-axis. That number is the ''b''. This is how you find the equation of a line. So let's say you have a line that look like the one on top. What's the equation? Well, let's start with the easiest part. Where does the line intersect? It goes through zero, so we know that it is y=mx+0 so far. Now for the slope. You would go up one, and over two, meaning that your equation is y=1/2x+0. Now let's check that. Let's use the coordinate point (4,2). Let's plug it in. 2=1/2*4+0. Is it true? 1/2*4= 2, and 2 +0 = 2. You then end up with 2=2. Congradulations! Your equation is correct!