Hi there. I work with people around the world to help them buy and sell businesses. I've been involved in the re-sale of dozens of franchises.
I would recommend you read my 2015 book Franchise Warnings. It contains a section on business valuation where I compare an independent business vs. a franchise. Available on Amazon or at www.FranchiseWarnings.com
My 2016 book; How To Sell My Own Business, also gives an insight on how small businesses are valued. I also have links to over 85 videos on buying and selling businesses at www.HowToSellMyOwnBusiness.com (book is also on Amazon.)
Should you want to discuss your particular case, simply arrange a call. If you want to move to an actual valuation, I'd be happy to help. There is more info at the above-mentioned website.
Ask around for comparable valuations from people who have already sold their franchises before. I'm sure there are plenty of stories online.
Ultimately, valuations are derived from a combination of current cash flows, profits, and future projected cash flows.
The question of whether or not anyone will actually buy your franchise at THAT valuation is a different story - and depends on the market, industry, climate, city, along with your own urgency to sell, etc...