How can I get div position in percentage from parent div

I am using drag and drop using jquery-ui. I am placing the draggable text on image. I need to find out the position of dropped text on image(In percentage) by using image div.

I have div like this:

<div>
<div>Some Text</div>
<div style="width=1000px; height:720px">
<img src="">
</div>
</div>