For Americans looking for an affordable meal out, geography can make a big difference in what they pay for a cheeseburger, fries and a soda.A $15 bill is still enough to cover a cheeseburger, fries and a soda in some U.S. cities, but not everywhere.A recent DoorDash State of Local Commerce report found that just four of the cities it analyzed had an average price below $15 for the meal: Austin and Laredo, Texas; Lincoln, Nebraska; and Detroit, Michigan.Austin was the cheapest at $12.94, according to DoorDash's so-called Cheeseburger Index, which tracks the average cost of a cheeseburger, fries...