The center of the intersection of Park Blvd and Broadway in Boise is 805.15 miles west
(and 81.57 miles south) of the nearest point on the 100° West meridian.
(That point is about 5.1 miles southeast of the center of Agar, South Dakota.)
The center of Boise, Idaho is at about 116.2 degrees west longitude.
Coordinates given in WikiPedia indicate a longitude of 21 degrees east. This puts the point at which this coordinate is set east of the 20 degree line.
80 degrees east longitude
Baghdad lies near the 45 east line of longitude.
Prime meridian, from which longitude is measured both east and west, is the main line of longitude.
Brazil, Paraguay, and Uruguay all lie entirely to the east of the 60w longitude line.
The Ural Mountains lie almost exactly on the 60 degrees east line of longitude.
121 degrees east longitude
Whether travelling to the West or to the East from the Prime Meridian (zero Longitude) the International Date Line is 180 degrees Longitude.
The 60 degrees east line of longitude runs through the Ural Mountains.
34 South, 18 East
You would be on the 110 degrees West line of longitude.