10 CHALLENGE PROBLEM Yen Luong owns a used pickup truck that she wants to sell A used vehicle guide shows that its average retail value is 17 600 She adds 1 700 for 4 wheel drive 475 for an entertainment system 800 for a special trim package and 225 for power locks She also adds 125 for a sliding rear window 325 for a towing package 250 for power windows and 3 125 for a diesel engine She deducts 675 for having a manual transmission She adds 450 for having less than the expected mileage What is the average retail price of Yen s vehicle