Can someone explain this problem to me?? After a price reduction of x%, an item has its price increased to its original value. What was the percent of increase? Express your answer as a common fraction in terms of x.

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Answer:

[tex]We\ are\ given\ that,\\Percent\ of\ reduction=x_-\\So,\\Let\ the\ percent\ of\ increase\ be\ x_+\\Let\ the\ original\ price\ of\ the\ item\ be\ y\\Let\ the\ price\ after\ the\ decrease\ be\ z\\.\\Hence,\\y-\frac{x_-}{100} =z\\ z+\frac{x_+}{100}=y\\By\ simply\ adding\ the\ equations,\\(y+z)+(- \frac{x_-}{100}+\frac{x_+}{100})=(z+y)\\Hence,\\- \frac{x_-}{100}+\frac{x_+}{100}=0\\Hence,\\ \frac{x_-}{100}=+\frac{x_+}{100}\\Hence,\\x_-=x_+\\[/tex]

[tex]Hence,\ the\ percent\ of\ increase\ is\ same\ as\ the\ percent\ of\ decrease.[/tex]