How do I draw a graph, y = mx + c, if I am only given m and a point that the line passes through?

Let's say we have the equation y = 2x + c and we are told that the line passes through the point (3, 4).  Our first step is to use the numbers from the point (3, 4), by substituting them into our equation. Like so: 4 = 2(3) + c (We have changed the y to 4 and the x to 3). Next all we need to do is solve this equation to find c. 4 = 6 + c, c = -2. And we are done.