Simba Travel Agency arranges trips for climbing Mount Kilimanjaro. For each trip, they charge an initial fee of \$100$100dollar sign, 100 in addition to a constant fee for each vertical meter climbed. For instance, the total fee for climbing to the Shira Volcanic Cone, which is 300030003000 meters above the base of the mountain, is \$400$400dollar sign, 400. Let yyy represent the total fee (in dollars) of a trip where they climbed xxx vertical meters.