"My brother lives in Moscow."
Translation:Мой брат живёт в Москве.
Russian nouns have different forms called "cases", depending on how they're used in the sentence or what preposition they follow. Москва is the nominative form, which is used for the subject of a sentence. Prepositional case is used after the prepositions в, на, о and при. Москва In prepositional case becomes Москве.
For students who have difficulty finding an effective method of typing Russian, you already have it installed as an option on your windows computer. Using that option will result in your ability to use an actual Russian style keyboard. This strikes me as a much better use of your time than learning some system almost as difficult as learning the Cyrillic alphabet itself.
Do an internet search for how to install the U.S. International keyboard. Follow that up with how to install the Russian keyboard option and the method to switch back and forth between your native language and your target language/s.
Once you have a Cyrillic keyboard available go on to the internet and find one of the many free sites that teach touch typing using a Russian keyboard map. It should take a couple of weeks work to get that down to where you can use it but with some difficulty. It is possible you may never get what you regard as good at using it.
However difficult all that sounds and however frustrating it is to actually do it, it is nothing compared to the lifelong effort to learn and retain a working knowledge of Russian.
Download and install your opertating system's Russian Language pack for your keyboard. I had a picture beside my monitor of the Cyrillic layout while using my PC, and you can literally just look at the thing on your phone if using that. Duolingo isn't going to accomodate one person who refuses to take steps to improve their own experience in exchange for making everyone else's experience worse. You should be learning to identify the actual symbols anyway.