Sundae Safari Truck

The Sundae Safari Ice Cream truck weighs 3,923lbs carrying 45 three galloon tubs of ice cream to the Blossom festival. On the way back from the festival, there are only 12 tubs left and the truck weighs 3,131 lbs. How much does the ice cream truck weigh when empty? The answer can be used as a promo code for 10% off a puzzle room experience. The code is valid until June 1, 2024.