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Proof:
1250 - 900 = 350 is the amount saved
350/1250 = 0.28 = 28% is the discount
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You take 28% of 1250 to get 350, then subtract off 350 to end up with 900
1250 - (28% of 1250) = 1250 - 0.28*1250 = 1250 - 350 = 900
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Or a shortcut is
1250*(1-0.28) = 1250*0.72 = 900
This is because the price is reduced by 28%, so you still pay the remaining 72%
