Quote Originally Posted by UChessmaster View Post
Take the fictional board and do a vertical cut in the middle, two pieces, 10 minutes, now take either piece and do an horizontal cut, 3 pieces, 15 minutes. I guess that`s how the teacher saw it, which is not necessarily wrong, and before someone comes trolling i never said the 20 minutes answer was wrong.
I edited my post while you were posting I think, but yes.

Your scenario assumes that the board is twice as long as it is wide btw, which isn't stated in the question.

Given the details of the question, I think it's pretty safe to say 20 is the only reasonable answer.