Joni, a freshmen at Central College, works part-time as a sandwich maker and delivery driver at Jimmys Johns in Pella. Included in her job application and the employee handbook is the following:

Employee covenants and agrees that, during his or her employment with the Employer and for a period of two (2) years after he or she will not have any direct or indirect interest in or perform services for any business which derives more than ten percent (10%) of its revenue from selling submarine, hero-type, deli-style, pita and/or wrapped or rolled sandwiches and which is located with three (3) miles of either [the Jimmy John's location in question] or any such other Jimmy John's Sandwich Shop.

Discuss the legality and enforceability of this non-compete clause as it pertains to Joni.