(1 point) Which of the following subsets of {\mathbb R}^{3\times 3} are subspaces of {\mathbb R}^{3\times 3}? A. The diagonal 3\times 3 matrices B. The 3\times 3 matrices with all zeros in the third row C. The non-invertible 3\times 3 matrices D. The symmetric 3\times 3 matrices E. The 3\times 3 matrices whose entries are all greater than or equal to 0 F. The 3\times 3 matrices in reduced row-echelon form

What's for breakfast? all people who ate at a certain restaurant were surveyed as to what they ordered on a particular sunday morning. 40 ate eggs 42 ate sausage 32 ate pancakes 13 ate sausage and eggs 15 ate pancakes and sausage 11 ate eggs and pancakes 6 ate all three items 3 people didn't eat any of the items how many people ate only pancakes? how many people ate at the resturant that morning? how many people didn't eat eggs?