What is an "extension"??

On Mar 10, 2:44*pm, Assigning drop down selections w / Value
<Assigning drop down selections w /
wrote:
Not sure if this can be done..

Looking to assign drop down selections a "value" for which, once selected,
can be multiplied by different cells to come up with an extension. *

More like assigning a menu of words with a value and then once user selects
that specific item along with another drop down value, an extension appears.

For Example

* *Tickets to Rome- $590.00 each
* *Tickets to Paris- $400.00 each
* *Tickets to New York-$320.00 each

*Multiple by:
* *1 Round Trip Passenger
* *2 Round Trip Passengers
* *3 Round Trip Passengers

Equals= Extension.

Possible through Excel?