Chena is building an igloo, a house made of snow. So far, she’s built the base of the house in the shape of a rectangular prism. Also, a tunnel for a hallway and doors have been dug straight through the igloo. How much snow has Chena used to build the base of the igloo after digging out the hallway. A rectangular prism with a length of 20 feet, width of 12 feet, and height of 7 feet. A smaller rectangular prism with length of 3 feet, width of 12 feet, and height of 5 feet is cut out of the larger prism.