Where is V15 and how do I find it?
There is a notation for V15 (low altitude IFR airway) in the southern portion of the top map in your question.



V15 is a Federal Airway, normally used for IFR operations and shown on IFR charts as well as VFR Sectionals. Federal Airways, unless otherwise notated, begin at 1200 AGL. These airways are Class E airspace. If you look in the legend of your Sectional Chart it describes this airspace.