Question

read the text.
knowing how to read a city map is a valuable skill. first, figure out your location on the map. check the street signs at the nearest intersection and use clues to help you find that intersection on the map. for example, if you are near a bridge or a park, look for those symbols on the map. the maps legend indicates what the symbols mean.
a maps compass rose reveals where north is. to establish direction, walk a block and revisit your map; compare where you were to where you are. in which direction did you travel? then locate your destination on the map.
the maps scale indicates distance ratios; for example, an inch may be equal to five hundred feet. now you know where you are, how to get where you are going, and how far you have to go!
which authors purpose is suggested by the text?
to describe to readers the features of different maps
to explain to readers how to navigate a city with a map

Explanation:

The text provides a series of steps on using a city map: figure out location, use map's legend, compass rose, scale. It's about navigation with a map, not just describing map features.

Answer:

to explain to readers how to navigate a city with a map