French fries are far and away the biggest money maker for fast-food restaurants. That’s partially the case because chains create a huge markup on fries, charging customers many times more for fries than what they pay for the raw potatoes. In fact, the markup can be as high as a staggering 3,900%. Plus, most fast-food chains use pre-cut, frozen fries making the golden brown side, even more, cost-effective than fast-food chains that make fresh-cut fries for real potatoes every day. […]