Percentage Practice Test 5 with solutions

Let the selling price of a book in year 2008 = x
Decrease percentage in the sale from year 2008 to 2009 = 80%
So, the sale of a book in year 2009 = (x – 80% of x)
$=\mathit{x}-\frac{80}{100}\mathit{x}=\frac{\mathit{x}}{5}$
Let the selling price of a book in the year 2010 = x
Increase percentage of the sale from year 2009 to 2010 $=\frac{\mathit{x}-\frac{\mathit{x}}{5}}{\frac{\mathit{x}}{5}}\times 100$
Required increase percentage = 400%