Consider a simplified example of a private carrier using the formula "$200 + 3x" to determine the operating cost of trips over a particular 100-mile lane, where x is the number of units carried n the truck and the $200 comprises $100 as the set up cost of a trip and $100 as the distance cost based on $1 per mile. 15. What total cost must the carrier cover if a shipper asks for a 30-unit shipment?