"She has a rich husband."
Translation:Ona ma bogatego męża.
Because that would be a wrong case. "mieć" needs Accusative, "mąż" is animate, so the only option is "męża".
Thanks, Jellei. I feel that the majority of the questions relating to Polish Duolingo (including mine) are related to the variety of cases - none of which are explained within the program. Perhaps each case should have several lessons associated with it? It's just a suggestion, but one I feel is necessary with this language.