# math

Compare the number of Facebook friends at the beginning of a month and at the end of that month, if …
a) it increased by 25% and then decreased by 40%
b) it decreased by 60% and then increased by 80%
c) it increased by 5% and then increased by 20%
d) it decreased by 10% and then decreased by 30%

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1. I will do the first, you do the rest in the same way

suppose you have x friends
after increase of 25% you have 1.25x
after decrease of 40% you are left with (.6)(1.25x) = .75x
effective change: decrease of 25%
(test it with some actual numbers)

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posted by Reiny
2. a) 1.25 * 0.60 = 0.75 so, down by 25%
and so on

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posted by oobleck

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