Let's say the item starts off at $100.
A 55% decrease means 100%-55% = 45% of the value is still there. The item is now worth 0.45*100 = 45 dollars.
Now increase this by 25%. The long way to do this is to add 25% of 45 onto 45
(25% of 45) + (45) = 0.25*45+45 = 11.25+45 = 56.25
Or, we can multiply 45 by 1.25 since the multiplier 1.25 represents a 25% increase
1.25*45 = 56.25
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The item was $100, it drops to $45 after the 55% decrease, then it is $56.25 after the 25% increase.
Let's compute the percent difference
A = 100 = old value
B = 56.25 = new value
C = percent difference
C = 100*(B-A)/A
C = 100*(56.25-100)/100
C = -43.75%
The negative C value indicates a percent decrease.
So combining a 55% decrease and a 25% increase leads to an overall decrease of 43.75%
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A shortcut is to multiply 0.45 and 1.25 to get 0.5625
Then subtract this from 1 to get 1-0.5625 = 0.4375
This is another way to see we have a 43.75% decrease.
