x
<html><body><h1>JavaScript Assignment</h1><h2>Addition Assignment</h2><h2>The += Operator</h2><p>x = 10 and y = 5, calculate x += y:</p><p id="demo"></p><script>let x = 10;let y = 5;x += y;document.getElementById("demo").innerHTML = "Value of x is: " + x;</script></body></html>