Which coordinates identify a location north of a city that has a latitude of N and a longitude of W?

To identify a location north of a city with coordinates N (latitude) and W (longitude), you would keep the longitude constant (W) and increase the latitude. For example, if the city's coordinates are N30° W90°, a location directly north could be N31° W90°, N32° W90°, and so on, depending on how far north you wish to go.