His claim is reasonable because 154÷25 6.16
6.16×2= 12.32 so it would be 12 dollars off!
There is a math app called desmos past the graph equations and it will show you the answer. But i will comment below and tell you the answer if you don't want to
Buying it 10% discount without tax is the best option. With card you still have the tax plus the card fee you pay annually to add to it. On the online purchase, you still have the tax plus the 5 shipping charge.
What do you have to do in that problem?
