[SOLVED] How would i get the angle between 2 block positions?

I'm currently making a mirror with ViewportFrames. It works as expected, but it still needs a lot of work. When you move your character for the right as an example, viewport's camera must turn too. I think it can be done with CFrame:fromMatrix() but wiki is too hard to understand. So, basically, i have the player position and the mirror's position, and i need to know something like a "line" between these two, changing camera's angle to line's angle.