Código HTML:
Ver original<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> var radio_1=false;
var radio_2=false;
function CheckunCheck(obj){
var checked=false;
switch (obj.id){
case "radio_1":
radio_1=!radio_1;
checked=radio_1;
break;
case "radio_2":
radio_2=!radio_2;
checked=radio_2;
break;
}
obj.checked=checked;
}
function Suma(isChecked, myValue)
{
tot = parseInt(document.form1.total.value);
myValue = parseInt(myValue);
if (isChecked.checked) document.form1.total.value = tot + myValue;
else document.form1.total.value = tot - myValue;
}
<form method="post" name="form1"> Motor 1
<input name="radio_1" id="radio_1" onclick="CheckunCheck(this);Suma(this,this.value)" type="radio" value="100" /></p> Motor 2
<input name="radio_2" id="radio_2" onclick="CheckunCheck(this);Suma(this,this.value)" type="radio" value="50" /></p> Extra 1
<input name="chec_1" id="chec_1" onclick="Suma(this,this.value)" type="checkbox" value="500" /></p> Total
<input name="total" type="text" value="0" /></p>
Ahi lo tienes, pero vaya perdida de tiempo pudiendo lo hacer con checkbox.