Answer: 0.65d (second choice)
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Explanation:
If you have a 35% discount, this means you save 35% but still pay 65% of the original price.
Notice how 35%+65% = 100%
Or you can think of it as 100% - 35% = 65%
Then we rewrite 65% into 0.65
If d is the original price, then d*0.65 = 0.65d is the price after the discount.
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As a slightly longer alternative method, we can say,
d = original price
discount = 35% of d = 0.35d
final price = d - 0.35d
final price = 1d - 0.35d
final price = (1-0.35)d
final price = 0.65d
