A shipping company uses the weight of packages to determine shipping prices. For any item 5 pounds or greater, the following equation gives the price, p(w), of shipping the item between two locations as a function of the item's weight, w, in pounds. The company does not use the following equation to determine shipping prices for items which are greater than 80 pounds.

p(w)=$3.50w+$5.50

determine the domain of p(w).