Today a shoe store took 20% off the price of a pair of shoes, and for the next 3 days, it will take 20% off the previous day's price. If the price of the pair of shoes yesterday was $200.00, what will be the price of the shoes 3 days from now?

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Answer 1 · 2016-07-27T11:51:37

#$81.92#

There are 2 ways to take off 20% from a number:

Method 1. Find 20% and subtract it.
#20% xx 200 = 40#

#$200 - $40 = $160#

Method 2. If 20% is being deducted, then 80% is left,
Find 80% straight ways.

#80% xx $200 = $160#

Using method 1 will mean we need to do a new calculation for each day and subtract to get the new amount.

Using method 2, we can just keep find 80% for each day.

Price yesterday: $200
Price today = #80% xx $200 = $160#

3 days from now: #160 xx80% xx80% xx80%#

This is the same as #160 xx0.8xx0.8xx0.8#

Or for ease of calculating: #160 xx0.8^3#

In 3 days time: Price = #$81.92#