SOLUTION: A number is increased by 2/5 of its value and then decreased by 2/5 of its new value. What is the ratio of the final value to the original ?

Question 852443: A number is increased by 2/5 of its value and then decreased by 2/5 of its new value. What is the ratio of the final value to the original ?
Answer by JulietG(1812) (Show Source): You can put this solution on YOUR website!
Let's use 100 for the sake of simplicity.
100 is increased by 40% ()
What is the new total?
140
140 is now decreased by 40%
140 * .6 (reciprocal) = 84
.
The final ratio is 100:84, or reduced to 25:21
ETA: I multiplied by .6 because that is the reciprocal of .4. It's the same as 100% - 40%. Just did a step in my head.
Here's without the reciprocal:
140 is now decreased by 40%.
140 * .4 = 56
140 - 56 = 84
.
I combined them by subtracting .4 from 1. Either way works. Sorry for the confusion.
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