difurios,
поле result я таки добавил с кнопой а чего нет в вашем коде закоментировал
<!DOCTYPE HTML>
<html>
<head>
<title></title>
</head>
<body>
<input type="radio" name="radio" id="radio" value="2830" onClick="show_visibility('Dop')">
<label for="radio"></label>
<input type="radio" name="radio" id="radio2" value="2810" onClick="show_visibility('Dop')">
<input type="radio" name="radio" id="radio3" value="1800" onClick="toggle_visibility('Dop')">
<input id="result" >
<button class="send" onclick="summ()" >summ</button>
<script language="JavaScript" type="text/javascript">
function summ()
{
var radio = document.getElementById("radio");
var radio2 = document.getElementById("radio2");
var radio3 = document.getElementById("radio3");
// var count = document.getElementById("count");
var result = document.getElementById("result");
var price = 0;
radio.checked && (price += parseInt(radio.value));
radio2.checked && (price += parseInt(radio2.value));
radio3.checked && (price += parseInt(radio3.value));
// price += parseInt(count.value) * parseInt(result.value);
result.value = price;
}
</script>