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Rocky Nelson was Founder and President of Arizona Airways from its founding in 1942 until its merger with Challenger and Monarch Airlines June 1 1950 to form  Frontier Airlines  headquartered in Denver  Colorado  .
 Frontier Airlines, Colorado
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: cities of residence, top members employees, members, alternate names, origin, state or provinces of residence, title of person, spouse, city of headquarters, NA, founded by, state or province of headquarters, employee of, countries of residence, country of birth, founded, subsidiaries, country of headquarters 
Text: {0} 
Answer:
 Frontier Airlines, Colorado