How do I tell my mother that a 77% increase is still a horrible deal?

I'm trying to tell my mom that even after a 76% discount, it's still an absolutely horrible deal and nearly quadruple the market price for a similar product. I am getting ready for a big "disagreement" because she is stubborn with her purchases.<br><br>&#x200B;<br><br>I agreed to help her buy a tablet to use for her online classes and said I would be happy to help her find a good deal. I even agreed to go with her to the brick and mortar, and then I found out it was an electronics store with a physical location. It's a scam store and I told her they're about to rob her blind; she can't believe in the possibility of being conned. Grudgingly she has agreed to check online prices. I send her my price sheet with market prices and price comparison with about 4 major retailers.<br><br>Then the salesperson calls her and asks her if she's still interested in the tablet and says they're offering her a 77% discount off of the marked price; she thinks she's being offered an unbeatable deal. I tell her I've done the math and it's still about 400% above market price. I'm preparing for her to say I'm wrong and I'm not supportive of her purchases. How can I explain to her in a liberal arts language that this is still a horrible deal?<br><br>&#x200B;<br><br>&#x200B;