1 2 TIME REMAIN 50:24 How could Theo check his work? Check all that apply. Theo solved n + 5 = 11 for the unknown. The steps he took are shown. He started with 5 tiles. He could substitute 5 forn in the original equation and add. He could substitute 6 for n in the original equation and add. Then he added tiles as he counted up to 11. He could subtract 5 from 11 and check that the answer is 6. He realized he added 6 more tiles to his original 5 to make 11. So he found the unknown to be 6. He could subtract 11 from 5 and check that the answer is 6. O He could put all the tiles in 1 pile to count them to see if there are 11 in all.