Solve the equation 2x + 4y = 16 for y.
Since 2 divides every term of this equation, we can work with a simpler equivalent equation. Let's cut this whole puppy in half. (Not a real puppy.) Divide both sides of the equation by 2 to find that
x + 2y = 8
Then, x = 8 - 2y.
Make it rain.