"There are a few ads in black and white."
Translation:Il y a quelques annonces en noir et blanc.
I don't know which sentence you had in previous lessons, but if you write "noire (in feminine) et blanc (in masculine)" it is wrong anyway and the same goes for "blanc et noire". Besides, mechanically, the system cannot accept translations with switches such as "noir et blanc" to translate "white and black" or vice-versa because it simply compares your answers with the list of correct translations we have registered in the database.
Thank you, I appreciate the help. Also, I think I understand now, partly from an explanation given to another learner. "en noir et blanc" is a fixed phrase and doesn't concur with the gender of the noun. Is that correct? Just to be certain about the first point, I'm taking my lead from the question, had the english in the question said "Advertisements" as opposed to the more colloquial "ads" I would have been more inclined to use "Publicités" than to have shortened it to "Pubs". Have I misinterpreted the colloquialism for the french translation ?