Min z = 1000X + 1500X + 3200X + 500X + 1900X + 700X + 920X + 2000X + 1100X + 3000X + 840X + 799X + 1600X + 2300X + 1500X + 1500X + 2000X + 1800X + 3400X + 2600X + 1300X + 3200X + 600X + 980X + 1000X + 2000X + 2500X + 700X + 640X + 1500X.