Product Price help

[salesafc]

I am selling group tickets and I want to add a additional price field where they can select to by additional tickets.

 

 

 

 

For example

 

 

Product is a 20 pack of group tickets for $60.00

(so you get 20 tickets for $60.00)

 

now

 

if the customer wants to add additional say one or five more tickets to the to the order.Can I add that additional price 

field? I looked at the help section, but cannot find anything.

 

any help would be greatly appreciated.