Translation:What day of the week is October tenth?
My answer was: What day of the week is October the 10th Duolingo says incorrect : what day of the week is October 10th. Please fix these irritating little irrelevancies and maybe focus more on the Japanese than half of it trying to reverse engineer it back into an American English form. In reality all we need to see is “what day is it on October 10th” But of course that is wrong too. The pedantic linguists will go into detail about the difference between 何日 V 何曜日 but it’s unhelpful at this low level of daily conversation. Keep it simple