subtraction.html

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Subtraction</title>
</head>
<body>
    <div>
        <p id="txt_1">A number</p>
        <div>
            <input type="text" id="a_num"/>
        </div>
        <div>
            <p></p>
        </div>
        <p id="txt_2">B number</p>
        <div>
            <input type="text" id="b_num"/>
        </div>
        <div>
            <p></p>
        </div>
        <button type="button" id="btn_1" onclick="btn_1()">Calculate A - B</button>
    </div>
    <script>
        function btn_1() {
            var a_num = document.getElementById("a_num").value
            var b_num = document.getElementById("b_num").value
            var a_number = parseInt(a_num)
            var b_number = parseInt(b_num)
            alert(a_number - b_number)
        }
    </script>
    <style>
        #btn_1 {
            font-size: 20px;
            font-family: sans-serif;
        }
        #a_num {
            font-size: 20px;
            font-family: sans-serif;
        }
        #b_num {
            font-size: 20px;
            font-family: sans-serif;
        }
        #txt_1 {
            font-size: 20px;
            font-family: sans-serif;
        }
        #txt_2 {
            font-size: 20px;
            font-family: sans-serif;
        }
    </style>
</body>
</html>