Answer :
The mistaken assumption is that the customer thinks the shoes are back to their original price.
The assumption is wrong because the price of the shoe is now lower than $150.
The cost of the shoe now is $126.
In order to retain the price of $150, the percentage decrease should have been 28.6%.
What is the cost of the shoe now?
Price of the shoe after it was increased : 1.4 x 150 = 210
Price of the shoe after it was decreases: (1 - 0.4) x 210
0.6 x 210 = $126
The percentage the price should be decreased for the price to be back to $150 = (150 / 210) - 1 = 28.9%
To learn more about percentages, please check: https://brainly.com/question/25764815
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