To make x the subject of the equation means to solve the equation for x (get x by itself on one side). We do the order of operations in reverse, because we are using inverse operations. First, add the 2 to both sides (to keep the equation “balanced” we must do the same thing to both sides). y+2=3x. Then divide both sides of the equation by 3 (or multiply both sides by 1/3.
The equation of a line is typically written as y=mx+b where m is the slope and b is the y-intercept. If you know two points that a line passes through, this page will show you how to find the equation of the line.