[quote name='nasum']how do you get the 20% on Discover? I went to my account and then went to Dell through the Discover shop zone but I don't see anything about an additional 10%.[/QUOTE]
In the Discover Reward section of their website, on the left-hand side, it's a link for "Double Cashback Bonus." Sign up for it and you'll get double cashback bonus, including online purchases. Online purchases are normally 10% cashback from Dell.com, so should be 20% back with this promo.