To solve this, you need to use the slope formula which is (y2-y1)/(x2-x1).
When you set it up, it should look something like this: (2-(-4))/(2-(-1)) which would simplify to 6/3 which would simplify to 2. This only finds your slope, however. Now that you know your slope, you can start by first setting up you equation in slope intercept form which should be in this format: y=mx+b
Since you already know the slope (m) and the x and y values (you can use either coordinate, I'm just using (2,2)) your equation would look something like this: 2=2(2)+b. After this, you solve for b which happens to be -2, making your slope intercept equation: y=2x-2.
Now you can convert to standard form. In standard form, you have to have the equation in this format: ax+by=c where there cannot be decimals, fractions, and everything needs to already have the greatest common factor taken out. When you do this, you first need to subtract over 2x which makes the equation look like this: -2x+y=-2. However, ax cannot be negative, so you multiply your entire equation by -1. You then get your answer: 2x-y=2