You increase the size of a page by 30%30%. then you decrease it by 30%30%. what is the size of the page now?

Lets use 1 to solve this problem because it is easiest to show. 

Multiply 1 by 1.3 for a 30% increase (1*1.3=1.3). 

Then multiply 1.3 by .7 for a 30% decrease. (1.3*.7=.91)  

Therefore the page had a 9% reduction from its original size or is 91% of its original size.