Usually a map will have what is called a SCALE on it, and that will allow you to look at the map and figure out how far it is from one point to the next.
For example, if you have a map in front of you and you are looking at the distance between YOURVILLE and THEIRVILLE, the two towns might be five inches apart.
Look at the scale. The scale might say, "One inch equals 50 miles." Well, how far away are the two towns?
Five inches x 50 miles per inch yields 250 miles.
THAT is how to read a map. You're welcome.
NOW you have to figure out what the "one inch" and the "miles" are in your problem. If the inches are "X" and the miles are "Y" in the example *I* gave you, then you could say "X" = 50 miles (given) and "Y" = 5x (5 times the value of "X" because the towns are five inches apart, or 250 miles). To express it in a formula, then, for THIS problem, you would say, 5x = y or, conversely, y = 5x. Another way to express that would be x = y/5.
All YOU have to do is to plug in the actual numbers from YOUR problem to the sample that I've provided. Easy peasey.