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.

Ok here we go ..there are plenty of ways to solve such math problems but we will go for the smartest and easiest ..5x+2y=7  -2x+6y=9we rearrange them into the following ..by multiplying the 1st equation by 2 it becomes 10x + 4y = 14we rearrange it and so it becomes 10x = 14 - 4yas for the second equation we multiply it by 5 and rearrange it so it becomes as to the following ..-10x + 30y = 45rearranging so 10x = 30y -45now 10x equals both 14 - 4y and 30y -45so   14 - 4y = 30y -4531 = 26yy= 31/26 = 1.19 or around 1.2so by now we can calculate x easily as  -2x+6y=9so 2x = 6y -9 = 6 * 31/26 - 9 = -1.84  then x = - 0.92 or around -0.9best luck!