so this means I can get a $5 amazon gift card for free because you have said that you can buy them at a 5% discount rate. if you have a $5 and would like to charge me how much will it be
5$ with 5% off is basically 0$

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Oh man there's a huge problem with your math in here :p
Well what 5% off means for a 5$ code, it means 4.75$ for it