You first have to turn 2x + 4y = -8 into y = mx + b before graphing. To do this, you subtract 2x from the left side of the equation because inverse operations. This will bring 2x to the right side. Now, you will have 4 = -2x + 8. However, you cannot have a number with y. Therefore, you must divide -8 and 2 by 4. You will get y = -1/2 x + 2 as your equation.
To graph -1/2x + 2, you must remember rise/run. Since it is NEGATIVE -1/2, your slope will go downwards (1 down, 2 across) starting from y = 2.
