Comment coûte-t-il? was the answer to the question: "How much does it cost?"
I hadn't heard "comment" in reference to cost, so I replied "Combien cela coute?" and it was wrong.
Comment? Combien?

Edith-M
November 4, 2013

toru e
November 4, 2013
That doesn't make sense, "Combien cela coûte?" is perfectly fine. One would use "Comment...?" if he/she didn't hear the price when it was given, so it almost sounds like a contextual question. Do you have the lesson number to reference?