Subtracting variables

Cant stop an object.

Hello,
I’ve been trying to make an item move on onload. I want to stop it if b – c = 10%. Below is my code. Thanks

function move() {
            var enem = document.getElementById("2");
            var elem = document.getElementById("1");
            var width = 1;
            var enemwidth = enem.style.left;
            var id = setInterval(frame, 100);
            var dif = enem.style.left - elem.style.left;
            function frame() {
            if (enem.style.left - elem.style.left == '10%') {
                clearInterval(id);
            } else {
                width++;
                elem.style.left = width + '%';
                //console.log(width, elem.style.left, dif);
            }
        }
        }