34° S and 58° W
This tells you that the city is south of the equator and in the Western Hemisphere. You can see on this map that you're looking for a city in South America.
Now, look at this map.
Do you see that this city is probably Montevideo?
34° S and 18° E
This one is the same distance south of the equator, but in the Eastern Hemisphere. Hmmm -- that places it in Africa.
What city do you see in South Africa that's located at these coordinates?
51° N and 0°
This is on the Prime Meridian and in the Northern Hemisphere. It's in the United Kingdom.
I'm sure you can find the rest of these. We'll be glad to check your answers.