I have a < div > element
I know:
width: 500px,
height: 250px,
background-size: "240% 320%" or "1200px 800px",
background-position: -807px -526px,
also I know original image size: { width: 600px height: 400px }
I need to calculate background-position in percents
and not only for this case, I need to do it dynamic, so need a formula