Mapping Center Answer:

You will need to acquire the 1:24,000 scale digital elevation model (DEM) for that quadrangle.  Depending on where you are, there are different sources, here is a USGS URL that describes where you can get that data:  http://edc2.usgs.gov/geodata/index.php

Once you have the data, you will need to use the Spatial Analyst extension's Slope Tool, which will produce a continuous surface of slope values.  There are a number of ways to then extract the 30-45 degree range; if you just need to show it on a map, just use the symbology tab of for your slope layer and exclude the values that are not within that range within a classified display (versus stretched).