Show different

depening on what radiobutton is checked

Hi everyone,
 I am currently building a page that asks the user to enter their details.
At the head of the page there are 4 radio buttons where the user choses whether it is just one passenger, two, three, or four.
If it is just one passenger then the form stays the same. However if they select two, three, or four passengers then more passenger <div>'s should appear to enter the details of the other passengers.
 
Any help would be excellent.
 
Here are my radiobuttons 

"width:120px; float:left">
"noOfPax1" Text="1 passenger" Checked="true" runat="server" GroupName="pax"/>

"width:120px; float:left">
&q ...